Journal articles: 'Fish aggregation'

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Hosn, Wafa Aboul, and John A. Downing. "Influence of Cover on the Spatial Distribution of Littoral-zone Fishes." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 8 (August 1, 1994): 1832–38. http://dx.doi.org/10.1139/f94-185.

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Littoral-zone fish are thought to reduce predation pressure by seeking refuge within macrophyte beds or near the lake bottom, or by aggregating. We used underwater video to measure the spatial aggregation of prey fishes in the littoral habitat. At low density, fish were more aggregated off the bottom in open habitats than when found off the bottom within macrophyte beds. At high densities, fish were primarily observed near the lake bottom, and the presence or absence of macrophyte beds had little influence on spatial behavior. No difference could be detected in the degree of aggregation seen in fish on the lake bottom inside or outside macrophyte beds. Our results lend field support to theoretical and laboratory research that suggests aggregative behavior in littoral-zone fish is strongly influenced by fish density and by habitat structure.

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Archer, Stephanie K., Scott A. Heppell, Brice X. Semmens, Christy V. Pattengill-Semmens, Phillippe G. Bush, Croy M. Mccoy, and Bradley C. Johnson. "Patterns of color phase indicate spawn timing at a Nassau grouper Epinephelus striatus spawning aggregation." Current Zoology 58, no. 1 (February 1, 2012): 73–83. http://dx.doi.org/10.1093/czoolo/58.1.73.

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Abstract Nassau grouper Epinephelus striatus are a large bodied, top level predator that is ecologically important throughout the Caribbean. Although typically solitary, Nassau grouper form large annual spawning aggregations at predictable times in specific locations. In 2003, The Cayman Islands Marine Conservation Board established protection for a newly rediscovered Nassau grouper spawning aggregation on Little Cayman, British West Indies. The large size of this aggregation provides a unique opportunity to study the behavior of Nassau grouper on a relatively intact spawning aggregation. During non-spawning periods Nassau grouper display a reddish-brown-and-white barred coloration. However, while aggregating they exhibit three additional color phases: “bicolor”, “dark”, and “white belly”. We video sampled the population on multiple days leading up to spawning across five spawning years. Divers focused a laser caliper equipped video camera on individual fish at the aggregation. We later analyzed the video to determine the length of the fish and record the color phase. Our observations show that the relative proportion of fish in the bicolor color phase increases significantly on the day leading up to the primary night of spawning. The increase in the proportion of the bicolor color phase from 0.05 early in the aggregation to 0.40 on the day of spawning suggests that this color phase conveys that a fish is behaviorally and physiologically prepared to spawn. Additionally, 82.7% of fish exhibiting dark or white belly coloration early in the aggregation period suggests that these color phases are not only shown by female fish as was previously posited.

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Ibrahim, Sakri, Julaihi Matusin, and Sukree Hajisamae. "Natural and Combination Fish Aggregating Devices (FADS) as Tools for Fish Aggregation in Lake Kenyir, Trengganu, Malaysia." ASEAN Journal on Science and Technology for Development 17, no. 2 (November 1, 2000): 39. http://dx.doi.org/10.29037/ajstd.114.

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Castro, J. J., J. A. Santiago, and V. Hernández-García. "Fish associated with fish aggregation devices off the Canary Islands (Central-East Atlantic)." Scientia Marina 63, no. 3-4 (December 30, 1999): 191–98. http://dx.doi.org/10.3989/scimar.1999.63n3-4191.

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Amarante, Cristina Fernandes do, Wagner de Souza Tassinari, José Luis Luque, and Maria Julia Salim Pereira. "Factors associated with parasite aggregation levels in fishes from Brazil." Revista Brasileira de Parasitologia Veterinária 24, no. 2 (June 12, 2015): 174–82. http://dx.doi.org/10.1590/s1984-29612015031.

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The degree of parasite aggregation is determined by a number of factors that are not well understood. In total, 3,746 fish from 73 species and their parasites were analyzed to determine associations between the degree of aggregation by taxon and specific characteristics of the fish. A multiple linear regression (95% confidence interval - CI) was used to show that in most taxa, the degree of parasite aggregation was significantly higher in freshwater fish and schooling fish but varied according to taxon in relation to gender, habitat and feeding habits. Parasite aggregations were also significantly increased in fish with a large number of parasitic larvae and greater body length in all evaluated taxa. Because the coefficients of determination of the models were lower than 60% for all taxa, other factors may be involved in parasite aggregation. Conversely, marked significance was observed for the tested variables in relation to taxon dependence, which indicates that additional studies should be performed for these factors using comprehensive databases with larger samples per parasite species.

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Hordyk, Adrian R., Neil R. Loneragan, Geoff Diver, and Jeremy D. Prince. "A cost-effective alternative for assessing the size of deep-water fish aggregations." Marine and Freshwater Research 62, no. 5 (2011): 480. http://dx.doi.org/10.1071/mf10260.

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Acoustic methodologies are important tools for monitoring deep-water fish and have the potential to provide high-precision estimates of aggregation size. However, they can be costly to design and implement for monitoring fish. Data from 2 years of scientific surveys of the spawning aggregations of orange roughy (Hoplostethus atlanticus, Collett, 1889) on the Cascade Plateau, Tasmania, collected using commercial fishing vessels and echosounders, were used to develop a cost-effective approach for estimating the size of deep-water aggregations. Criteria were developed to standardise the identification of orange roughy echo-traces from acoustic data from 23 surveys in 2001 and 19 in 2005. The spawning condition of the fish was monitored simultaneously with the acoustics in each year (n = 29 trawls each year). The volumes of the aggregations were estimated throughout the survey period. Although the precision of the estimated aggregation size is low, large amounts of data can be collected over extended periods by using this approach and the equipment on standard commercial fishing echosounders. Aggregation volumes varied markedly during each spawning season and changes in volume appear to be linked to the spawning biology. Monitoring the spawning biology, therefore, provides crucial complementary information for interpreting estimates of aggregation size from acoustic surveys.

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Johannes, Mark R. S. "Prey Aggregation Is Correlated with Increased Predation Pressure in Lake Fish Communities." Canadian Journal of Fisheries and Aquatic Sciences 50, no. 1 (January 1, 1993): 66–73. http://dx.doi.org/10.1139/f93-008.

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Aggregations of prey fish, golden shiner (Notemigonus crysoleucas), were examined during 7 yr of predator manipulations in two lakes to determine whether they responded to changes in predation pressure and varied with time-of-day, age, and habitat. Regression analysis was used to examine aggregation in 12 replicate prey densities from two time periods, two ages, two habitats, three sample series, and seven predator densities. Aggregation was assessed as the variance of mean densities for each treatment combination. Multiple regression and ANCOVA analyses indicated that (1) golden shiner aggregated more during day than night, (2) their aggregation was positively related to predator density, (3) young shiner aggregated more than older ones at low predator densities, and (4) aggregation in older shiner was more responsive to increased predator densities than aggregation in younger shiner. These results provide empirical evidence that golden shiner aggregation patterns respond to predation pressure and the response varies with time and age. These results also suggest that variance in net catches can provide an index of fish aggregation and that aggregation observed at the population level is not solely dependent on species and density, but is a behavioural response mediated by several factors including predators.

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Mangubhai, Sangeeta, Muhammad Saleh, Suprayitno, Andreas Muljadi, Purwanto, Kevin L. Rhodes, and Katherina Tjandra. "Do Not Stop: The Importance of Seamless Monitoring and Enforcement in an Indonesian Marine Protected Area." Journal of Marine Biology 2011 (2011): 1–11. http://dx.doi.org/10.1155/2011/501465.

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The harvesting of groupers (Serranidae) in Indonesia for the live reef food fish trade (LRFFT) has been ongoing since the late 1980s. Eight sites in Komodo National Park that included two fish spawning aggregation (FSA) sites were monitored for groupers and humphead wrasse,Cheilinus undulatus, from 1998 to 2003 and from 2005 to 2008 to examine temporal changes in abundance and assess the effectiveness of conservation and management efforts. Monitoring identified FSA sites for squaretail coralgrouper,Plectropomus areolatus, and brown-marbled grouper,Epinephelus fuscoguttatus. Both species formed aggregations before and during full moon from September to December, prior to lapses in monitoring (2003–2005) and in enforcement (2004-2005). Following these lapses, data reveal substantial declines inP. areolatusabundance and the apparent extirpation of one aggregation at one site. Other non-aggregating species targeted by the LRFFT showed similar declines at three of eight monitored sites. This paper highlights the impact of FSA fishing and the need for a seamless monitoring and enforcement protocol in areas where aggregation fishing pressure is high. Within Komodo National Park, local fishers, particularly those operating on behalf of the LRFFT, pose a serious threat to population persistence of species targeted by this trade.

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Smith, Barry D., Mark W. Saunders, and Gordon A. McFarlane. "Use of a Binomial–Normal Functional Model to Demonstrate that the Sex and Age Composition of Pacific Hake (Merluccius productus) Aggregations Affects Estimates of Mean Lengths-at-Age." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 8 (August 1, 1992): 1657–69. http://dx.doi.org/10.1139/f92-185.

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We present statistical evidence that estimates of mean length-at-age from a single aggregation of Pacific hake (Merluccius productus) are unlikely to represent those for the entire local population because fish length varies with age and sex, and fish aggregations are probably structured by fish size. We present series of simple linear relationships between estimates of mean length-at-age from hake sample sets and both the proportion of males and the proportions-at-age in those sample sets. To determine these relationships, we developed a likelihood-based model which incorporated model and sampling uncertainty in estimates of mean lengths-at-age, and sampling uncertainty in the estimated proportions of males or proportions-at-age. The results show that if fish length varies with sex or age, then the mean lengths-at-age estimated from a single sample set will be predictably, although perhaps modestly, influenced by the age and sex composition of the sample set. Thus, estimates of population mean lengths-at-age, and other sex–age–size statistics of fish that form aggregations, should be based on the premise that an aggregation of fish, not an individual fish, is the basic sampling unit.

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NAKASHIMA, TOSHIKO, and TATSURO MATSUOKA. "Ghost-fishing mortality and fish aggregation by lost bottom-gillnet tangled around fish aggregation device." NIPPON SUISAN GAKKAISHI 71, no. 2 (2005): 178–87. http://dx.doi.org/10.2331/suisan.71.178.

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Crisafulli, B. M., D. V. Fairclough, I. S. Keay, P. Lewis, J. R. How, K. L. Ryan, S. M. Taylor, and C. B. Wakefield. "Does a spatiotemporal closure to fishing Chrysophrys auratus (Sparidae) spawning aggregations also protect individuals during migration?" Canadian Journal of Fisheries and Aquatic Sciences 76, no. 7 (July 2019): 1171–85. http://dx.doi.org/10.1139/cjfas-2017-0449.

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Understanding migration dynamics of fishes that aggregate-spawn is critical if spatiotemporal closures to fishing are expected to protect them. Concern over fishing of Chrysophrys auratus spawning aggregations in embayments near a west Australian city led to an annual 4-month spatial fishing closure. However, the extent to which it protects fish migrating to and from aggregations is unclear. Acoustic telemetry demonstrated a bimodal pattern of entry to and departure from the main embayment via only one of several pathways. Among years, 33%–56% of fish occurred in the pathway prior to the closure, but most left before it ceased. Fish were detected within the closure in multiple but not always consecutive years. Variation in migration timing and aggregation philopatry may alter capture risk, but pre- and postspawning migratory fish are fished in the main pathway and adjacent reefs, which would presumably impact spawning aggregation biomass. Assessment of this would assist in understanding whether expansion of the closure’s spatial and temporal limits is necessary to ensure spawning biomass or whether current management is sufficient.

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Stockwell, Jason D., Thomas C. Weber, Adam J. Baukus, and J. Michael Jech. "On the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling." ICES Journal of Marine Science 70, no. 1 (July 27, 2012): 196–203. http://dx.doi.org/10.1093/icesjms/fss139.

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Abstract Stockwell, J. D., Weber, T. C., Baukus, A. J., and Jech, J. M. 2013. On the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling. – ICES Journal of Marine Science, 70:196–203. Small pelagic fish can play an important role in the structure and function of ecosystems, and there is increasing interest in their non-market value. At the scale of fish aggregations, however, the impact of fishing has received relatively little attention, with most effort devoted to impacts of vessel and gear avoidance on stock size estimates. We used concurrent deployment of a downwards-looking echosounder (Simrad ES60 system) and an omnidirectional sonar (Simrad SP90 system) during commercial pairtrawling operations for Atlantic herring (Clupea harengus) in the Gulf of Maine to examine their potential for studying the impacts of fishing on herring aggregations. We compared a number of aggregation metrics to illustrate similarities and differences between the two systems, and then qualitatively examined their properties during and after pairtrawling events to illustrate potential applications. Our results suggest that using both downwards-looking and omnidirectional systems provides complementary information on fish aggregation metrics. Future applications of these systems in before–after–control-impact (BACI) designs may help inform management agencies when evaluating potential impacts of fishing at the time and space scales of pelagic fish aggregations.

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Sprague, Mark W., and Joseph J. Luczkovich. "Modeling fish aggregation sounds in very shallow water to estimate numbers of calling fish in aggregations." Journal of the Acoustical Society of America 129, no. 4 (April 2011): 2434. http://dx.doi.org/10.1121/1.3587960.

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SASAKI, TOMOKO, and KKUNIHIKO KONNNO. "Thermal aggregation of fish myosin rod." Fisheries science 68, sup2 (2002): 1659–60. http://dx.doi.org/10.2331/fishsci.68.sup2_1659.

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Chan, Julian K., and Tom A. Gill. "Thermal Aggregation of Mixed Fish Myosins." Journal of Agricultural and Food Chemistry 42, no. 12 (December 1994): 2649–55. http://dx.doi.org/10.1021/jf00048a001.

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Neilson, John D., Donald Clark, Gary D. Melvin, Peter Perley, and Chris Stevens. "The diel-vertical distribution and characteristics of pre-spawning aggregations of pollock (Pollachius virens) as inferred from hydroacoustic observations: the implications for survey design." ICES Journal of Marine Science 60, no. 4 (January 1, 2003): 860–71. http://dx.doi.org/10.1016/s1054-3139(03)00068-7.

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Abstract The characteristics of pollock (the synonymous European common name is saithe) pre-spawning aggregations were described at two locations with contrasting bathymetric features on the Scotian Shelf, off the Canadian Maritimes. The data were collected using a split-beam echosounder onboard a research vessel, augmented with periodic, bottom-trawl samples. Pollock form aggregations each fall that persist at the same location over time. Such aggregations appeared to be associated with spawning. Hydroacoustic information indicates that pollock become more densely aggregated at night. This could reflect movement away from the study area during the day, or changes in the proportion of pollock in the acoustic dead zone over the 24-h period. The hydroacoustic information indicates that while pollock can occur up to 30 m off bottom, the greatest proportion remains within 1–5 m off bottom during both day and night. The length composition of the pollock aggregations differed between the two sites, with larger fish found at the site further offshore. Within an aggregation, there was spatial heterogeneity with respect to fish size, with larger fish found primarily within the core area of aggregation as shown by the hydroacoustics. An appropriate survey design for obtaining an index of abundance for pollock would reflect both the contagious (patchy) distribution as they prepare to spawn, and the diel differences in the availability of the fish to the hydroacoustic-sampling gear.

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Erisman, Brad E., Larry G. Allen, Jeremy T. Claisse, Daniel J. Pondella, Eric F. Miller, and Jason H. Murray. "The illusion of plenty: hyperstability masks collapses in two recreational fisheries that target fish spawning aggregations." Canadian Journal of Fisheries and Aquatic Sciences 68, no. 10 (October 2011): 1705–16. http://dx.doi.org/10.1139/f2011-090.

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Fisheries that target fish spawning aggregations can exhibit hyperstability, in which catch per unit effort (CPUE) remains elevated as stock abundance declines, but empirical support is limited. We compiled several fishery-dependent and fishery-independent data sets to assess stock trends in the barred sand bass ( Paralabrax nebulifer ) and the kelp bass ( Paralabrax clathratus ) in southern California, USA, evaluate the interaction between spawning aggregations and fishing activities, and test for hyperstability. Annual and seasonal trends from fisheries and population data indicate that regional stocks of both species have collapsed in response to overfishing of spawning aggregations and changes in environmental conditions. The aggregating behavior of fish and persistent targeting of spawning aggregations by recreational fisheries combined to produce a hyperstable relationship between CPUE and stock abundance in both species, which created the illusion that population levels were stable and masked fishery collapses. Differences in the rate of decline between the two species may be related to the size, duration, and spatial distribution of their spawning aggregations. Results of this study provide empirical evidence of hyperstability in aggregation-based fisheries and demonstrate that CPUE data be used with caution and given low weight when fishery-independent data are available.

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Henderson, M. J., J. K. Horne, and R. H. Towler. "The influence of beam position and swimming direction on fish target strength." ICES Journal of Marine Science 65, no. 2 (February 5, 2008): 226–37. http://dx.doi.org/10.1093/icesjms/fsm190.

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Abstract Henderson, M. J., Horne, J. K., and Towler, R. H. 2007. The influence of beam position and swimming direction on fish target strength. – ICES Journal of Marine Science, 65: 226–237. Fish orientation is consistently identified as a major influence on fish target strength (TS). Generally, orientation is defined as the tilt angle of the fish with respect to the acoustic transducer, whereas a more accurate definition includes tilt, roll, and yaw. Thus far, the influences of roll and yaw on fish TS have only been examined cursorily. We used in situ single-target data to create fish tracks, to estimate fish tilt and yaw, and correlated these estimates with TS. The results show that tilt, yaw, and beam position have a significant influence on fish TS. To investigate further how yaw and beam position affect TS, we calculated the expected backscatter from each fish within simulated fish aggregations using a backscatter model. The TS of individual fish at 38 and 120 kHz varied by as much as 11 and 19 dB with changes in yaw and beam position. Altering the fish’s tilt, yaw, and beam position resulted in TS differences of 14 and 26 dB at 38 and 120 kHz, respectively. Orientation had a minimal influence on an aggregation’s average TS if the aggregation had a variable tilt-angle distribution and was dispersed throughout the acoustic beam.

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Parsons, Miles J. G., Iain M. Parnum, and Robert D. McCauley. "Visualizing Samsonfish (Seriola hippos) with a Reson 7125 Seabat multibeam sonar." ICES Journal of Marine Science 70, no. 3 (February 24, 2013): 665–74. http://dx.doi.org/10.1093/icesjms/fst009.

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Abstract Parsons, M. J. G., Parnum, I. M., and McCauley, R. D. 2013. Visualizing Samsonfish (Seriola hippos) with a Reson 7125 Seabat multibeam sonar – ICES Journal of Marine Science, 70: 665–674. In Western Australia, aggregations of Samsonfish (Seriola hippos) form each summer to spawn in waters west of Rottnest Island. In this study, a Reson 7125 Seabat multibeam sonar (400 kHz) was pole mounted aboard a 21.6 m vessel, conducting acoustic transects to acquire acoustic backscatter simultaneously from a midwater aggregation of S. hippos and the wreck it surrounded. The processed backscatter produced high-resolution visualizations of both the fish and seabed. During a 15 min period, the centroid of the aggregation moved 91 m around the eastern and northeastern side of the wreck and probably exhibited lateral vessel avoidance behaviour from the survey vessel. Additionally, a northeasterly current at the site was inferred from subtle habitat features, suggesting that at the time of the survey the aggregation preferred to remain upcurrent of the wreck. These findings confirmed that the S. hippos aggregations do not necessarily remain directly above the wrecks and do not always remain sedentary. Aggregation acoustic density packing at the survey site was observed at 12.7 ± 2.4 m3 per fish, equivalent to ∼1.6 ± 0.1 body lengths nearest-neighbour distance.

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Dassow, Colin J., Alexander J. Ross, Olaf P. Jensen, Greg G. Sass, Brett T. van Poorten, Christopher T. Solomon, and Stuart E. Jones. "Experimental demonstration of catch hyperstability from habitat aggregation, not effort sorting, in a recreational fishery." Canadian Journal of Fisheries and Aquatic Sciences 77, no. 4 (April 2020): 762–69. http://dx.doi.org/10.1139/cjfas-2019-0245.

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The relationship between angler catch rates and fish abundance can contribute to or hinder sustainable exploitation of fisheries depending on whether catch rates are proportional to fish abundance or are hyperstable. We performed a whole-ecosystem experiment in which fish abundance was manipulated and paired with weekly angler catch rate estimates from controlled experimental fishing. Catch rates were hyperstable (β = 0.47) in response to changes in fish abundance. By excluding effort sorting (i.e., catch rates remaining high because less skilled anglers leave the fishery as abundance declines), our experiment isolated the influence of fish aggregation as a driver of hyperstability. Spatial analysis of catch locations did not identify clustering around specific points, suggesting that loose aggregation to preferred habitat at the scale of the entire littoral zone was enough to maintain stable catch rates. In our study, general, non-spawning, habitat preferences created loose aggregations for anglers to target, which was sufficient to generate hyperstability. Habitat preferences are common to nearly all fishes and widely known to anglers, suggesting that many harvest-oriented recreational fisheries can be expected to exhibit hyperstability.

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Fulton, Elizabeth, David Kault, Bruce Mapstone, and Marcus Sheaves. "Spawning season influences on commercial catch rates: computer simulations and Plectropomus leopardus, a case in point1." Canadian Journal of Fisheries and Aquatic Sciences 56, no. 6 (June 1, 1999): 1096–108. http://dx.doi.org/10.1139/f99-046.

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Spatial and temporal closures of sections of the marine environment are proposed frequently as fishery management devices, particularly when specific areas, such as spawning aggregations, can be identified. The ultimate effectiveness of spawning area closures is unknown, as spawning-related determinants of catch rate have not been studied. A simulation model, based on existing biological and fisher information, was constructed to examine the most important determinants of the spawning season catch rates using the protogynous aggregative spawner Plectropomus leopardus (Family Serranidae, Subfamily Epinephelinae) as a test case. Model output indicated that spawning season catches rose as long as catchability of spawners was equal to or greater than that of nonspawners. Greatest increases in catch were produced by fish moving from habitats inaccessible to fishers into regularly fished locations during migrations to spawning aggregations. Elevated catches were not simply dependent on the targeting of aggregations by fishers. Small-scale spatial closures around spawning aggregation sites would not be sufficient to protect the spawning stock of fish such as P. leopardus, but larger scale closures during the spawning season may be useful even when fishers are not targeting spawning aggregations.

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丁, 思哲. "Fish Aggregation Model Based on Particle Swarm Theory—Automatic Modeling of the Whole Process of Fish Aggregation." Computer Science and Application 11, no. 03 (2021): 729–40. http://dx.doi.org/10.12677/csa.2021.113075.

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Mello, L. GS, and G. A. Rose. "Using geostatistics to quantify seasonal distribution and aggregation patterns of fishes: an example of Atlantic cod (Gadus morhua)." Canadian Journal of Fisheries and Aquatic Sciences 62, no. 3 (March 1, 2005): 659–70. http://dx.doi.org/10.1139/f04-227.

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Geostatistical methods were used to (i) quantify fish aggregation patterns over a range of scales (100 m to 67 km) using both simulated and acoustic density data of Atlantic cod (Gadus morhua) and (ii) examine how changes in aggregation patterns influenced the precision of geostatistical density indices. Variogram parameters (range, sill, and nugget) reflected changes in distribution patterns. Variograms of dispersed and low-density aggregations had large range and small sill and nugget values. In contrast, when fish were aggregated in a small portion of the study area, the range was low and the sill and nugget large. The precision of density indices (coefficient of variation) was below 20% in all cases but at a maximum during summer when cod were broadly distributed in small, moderate to dense aggregations. Geostatistical modeling allowed us to describe and quantify distribution patterns of fish density over different scales of observation, comparisons of spatiotemporal changes in density distribution, and estimations of the precision of density indices while accounting for the effects of heterogeneous distributions, outliers and the typically large number of zero and low-density observations. Geostatistical methods have particular applicability to fishes exhibiting gregarious behaviour and seasonally variable distributions, which include many temperate and high-latitude fish species.

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Machaieie, Sidonio, and Isabel M. Silva. "Spawning aggregations of fish in Cabo Delgado, Northern Mozambique: An interview-based survey of artisanal fishers." Western Indian Ocean Journal of Marine Science 19, no. 1 (October 29, 2020): 33–43. http://dx.doi.org/10.4314/wiojms.v19i1.3.

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Seasonal aggregations at specific sites are common among some fish species. Experienced fishermen know where and when these aggregations happen, often targeting these spawning sites to increase their catch. This strategy can further contribute to endangering the survival of these species, especially for those already threatened by other forms of pressure. This study contributes knowledge to the spawning aggregation of fish in the north of Mozambique following survey work conducted around Cabo Delgado Province in six coastal villages in 2016, 2017 and 2018. The objectives of the study were 1) to identify the species and sites of spawning aggregation and 2) to determine the timing of spawning aggregations. Data collection consisted of interviews targeting the most experienced fishermen to obtain information on these subjects. The results indicate that out of 124 fishermen interviewed, 59% had knowledge of spawning aggregations. The information collected from fisher interviews revealed that there are at least six spawning locations and at least eight species aggregate to spawn (Leptoscarus vaigensis, Lethrinus harak, Lethrinus nebulosus, Lethrinus obsoletus, Lethrinus olivaceus, Plectorhinchus gaterinus, Plectorhinchus schotaf, Siganus sutor). Only Siganus sutor was reported to spawn in at least one of the fishing areas used by every village. The timing of spawning aggregations most reported by fishermen was during the Kusi (South) monsoon period.

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Kawamura, Gunzo, Tomohiro Matsushita, Mikio Nishitai, and Tatsuro Matsuoka. "Blue and green fish aggregation devices are more attractive to fish." Fisheries Research 28, no. 1 (August 1996): 99–108. http://dx.doi.org/10.1016/0165-7836(96)00478-x.

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Dempster, T., P. Sanchez-Jerez, I. Uglem, and P. A. Bjørn. "Species-specific patterns of aggregation of wild fish around fish farms." Estuarine, Coastal and Shelf Science 86, no. 2 (January 2010): 271–75. http://dx.doi.org/10.1016/j.ecss.2009.11.007.

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Li, Guangning, Shuangke Sun, Haitao Liu, and Tiegang Zheng. "Optimizing the entrance location for a fish pass facility with limited attraction flow in a large river — A case study of the Jinsha River, China." Canadian Journal of Civil Engineering 46, no. 9 (September 2019): 847–57. http://dx.doi.org/10.1139/cjce-2018-0523.

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The fish pass facility of the Suwalong hydropower project (SHP) is one of the fish pass facilities in the Jinsha River with limited attraction flow. The bed elevation was raised and a shunt wall was added to optimize aggregation zones in the tailrace channel of the SHP. The flow field, fish migration corridors, and aggregation zones were analyzed using computational fluid dynamics software Flow-3D. Raising the bed elevation can accelerate the water, and new velocity barriers can be formed. Adding a shunt wall can split the flow. These two methods are effective for creating fish migration corridors and aggregation zones in the tailrace discharge. As the fish pass facility attraction flow cannot compete with the main current of the river, it is reasonable to first attract the fish from the river into the aggregation zone in the tailrace channel through the tailrace discharge and then set the entrance within the zone. These two methods were utilized to enhance the attraction efficiency through optimizing the entrance location.

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Akyol, Okan, Tevfik Ceyhan, F. Ozan Düzbastılar, Aytaç Özgül, and Halil Şen. "Wild fish diversity around the sea-cage fish farms in the Aegean Sea." Vol:36 Issue:3 36, no. 3 (September 15, 2019): 271–83. http://dx.doi.org/10.12714/egejfas.2019.36.3.08.

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Structures, floating on the surface of the ocean attract both juvenile and adult fishes in great numbers and diversity. Natural and artificial Fish Aggregation Devices (FADs) in open seas are widely recognised for their capacity to attract pelagic fishes. It can be assumed that floating sea-cages act as a kind of FAD. Even, fish aggregations beneath the sea-cages increase much more by the influence of feeding. In this study, aggregations of wild fish were counted around six sea-cage fish farms in both northern and southern Aegean Sea. Each fish farm cultivated Sparus aurata and Dicentrarchus labrax and the farms deployed between 720 m and 3 km far from the coast. Between July 2015 and July 2017, assemblages of wild fish were counted bimonthly on two separate days at each of these farms. The Rapid Visual Counts (RVC) in five minutes with SCUBA and covering 11250 m3 were performed for six times within each farm. A total of 40 species, belonging to 22 families were recorded at fish farms, with 3 families, Sparidae (7 species), Carangidae (6 species) and Mugilidae (4 species) being particularly abundant. The results of the study and other studies conducted in other parts of the Mediterranean were merged; it was found that a total of 99 fish species were listed around sea-cage fish farms in the Mediterranean Sea.

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Priatna, Asep, and Mahiswara Mahiswara. "PENGARUH CAHAYA LAMPU TERHADAP POLA AGREGASI IKAN DI BAGAN TANCAP PERAIRAN KEPULAUAN SERIBU." Jurnal Penelitian Perikanan Indonesia 15, no. 2 (February 2, 2017): 141. http://dx.doi.org/10.15578/jppi.15.2.2009.141-149.

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Penelitian ini bertujuan untuk mempelajari pola agregasi ikan di bawah pengaruh cahaya lampu bagan tancap. Penelitian dilaksanakan pada bulan Mei 2005 di Kepulauan Seribu. Pengamatan pola agregasi ikan dilakukan dengan menggunakan alat akustik Simrad EY500. Data intensitas cahaya diambil dengan menggunakan light meter LI-250, serta verifikasi hasil tangkapan untuk memperkuat hasil analisis. Analisis meliputi interpretasi visual berbasis pada presentasi grafik yang merupakan dasar bagi penafsiran data dan penyusunan informasi. Pengaruh intensitas cahaya yang berbeda terhadap agregasi ikan mempunyai pola yang tidak sama, baik nilai intensitas cahaya optimumnya, besarnya agregasi, maupun posisi kedalaman untuk nilai agregasi terbesar. Proses pengumpulan ikan pada awal penyinaran dengan perlakuan jenis lampu petromak lebih cepat dibanding dengan hasil perlakuan lampu mercuri. Ikan akan beradaptasi terhadap variasi iluminasi cahaya sehingga selama proses pencahayaan terjadi migrasi. The research objective was to study fish aggregation pattern under light influence set in stationary bamboo lift net. This research was conducted on May 2005 in Seribu Islands waters. Simrad EY-500 echosounder was used to observe the fish aggregation. Light meter LI 250 was used to measure light intensity level and catch data for supporting the analysis result. Data analyzed by visual description based on graph presentation were used as data interpretation and information. The influence of different light intensity on fish aggregation had different pattern especially for optimum value of light intensity, maximumvalue of fish aggregation, and depth layer of the maximum value of fish aggregation. For fish aggregation under light of kerosene pressured lamps was quicker than mercury lamps in the early of illumination process. Fish will adapt to various light illumination, so that during illumination process the migration of fish is occured.

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Yusfiandayani, Roza, Bambang Riyanto, Mohamad Rafi, and Heriyanto. "Productivity of Amino Acid Fish Aggregation at Raft Liftnet in Palabuhanratu Waters, Sukabumi." Jurnal Ilmu Pertanian Indonesia 24, no. 2 (April 26, 2019): 135–43. http://dx.doi.org/10.18343/jipi.24.2.135.

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Huang, Tingjie, Yan Lu, and Huaixiang Liu. "Effects of Spur Dikes on Water Flow Diversity and Fish Aggregation." Water 11, no. 9 (August 31, 2019): 1822. http://dx.doi.org/10.3390/w11091822.

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As a typical waterway modification, the spur dike narrows the water cross section, which increases the flow velocity and flushes the riverbed. Meanwhile, it also protects ecological diversity and improves river habitat. Different types of spur dikes could greatly impact the interaction between flow structure and local geomorphology, which in turn affects the evolution of river aquatic habitats. Four different types of spur dikes—including rock-fill, permeable, w-shaped rock-fill, and w-shaped permeable—were evaluated using flume experiments for spur dike hydrodynamics and fish aggregation effects. Based on Shannon’s entropy, an index for calculating water flow diversity is proposed. Additionally, the impact of the different spur dikes on water flow diversity and the relationship between water flow diversity and fish aggregation effects were studied. The water flow diversity index around the spur dike varied from 1.13 to 2.96. The average aggregation rate of test fish around the spur dike was 5% to 28%, and the attraction effect increased with increasing water flow diversity. Furthermore, we plotted the relationship between water flow diversity index and average fish aggregation rate. A fish hydroacoustic study conducted on the Laohutan fish-bone dike in the Dongliu reach of downstream Yangtze River showed that the fish aggregation effect of the permeable spur dike was greater than the rock-fill spur dike. These research results could provide theoretical support for habitat heterogeneity research and ecologically optimal design of spur dikes.

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Appenzeller, A. R., and W. C. Leggett. "Bias in Hydroacoustic Estimates of Fish Abundance due to Acoustic Shadowing: Evidence from Day–Night Surveys of Vertically Migrating Fish." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 10 (October 1, 1992): 2179–89. http://dx.doi.org/10.1139/f92-240.

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We investigated the hypothesis that fish schooling behavior leads to underestimation of fish abundance when assessed by acoustic methods. Current methods for acoustic quantification of fish abundance rely on the assumption that fish biomass and numerical fish abundance are linearly related to acoustic scattering under all natural fish densities. However, cage experiments as well as field observations have indicated that acoustic shadowing effects occur at very dense and large aggregations of fish. Acoustic surveys of the pelagic fish community of Lake Memphremagog, Quebec, were conducted when fish were aggregated and dispersed. These differences in aggregation were related to diel responses to light levels. We found that estimates of fish abundance, as measured by echo integration, were consistently and significantly lower when fish were aggregated in dense schools. This bias was not due to diel changes in average echo level per fish, which exhibited no relationship to diel changes in vertical and hortizontal distributions. We conclude that the reduced abundance estimates obtained when fish were aggregated resulted from acoustic shadowing. Our data suggest that this bias may be as large as 50%.

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Le Gall, J. "Mechanisms and effects of the aggregation of tuna by Fish Aggregating Devices (FADs)." Aquatic Living Resources 13, no. 4 (August 2000): 181–82. http://dx.doi.org/10.1016/s0990-7440(00)01067-6.

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Welicky, Rachel L., and Paul C. Sikkel. "Variation in occurrence of the fish-parasitic cymothoid isopod, Anilocra haemuli, infecting French grunt (Haemulon flavolineatum) in the north-eastern Caribbean." Marine and Freshwater Research 65, no. 11 (2014): 1018. http://dx.doi.org/10.1071/mf13306.

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Parasites constitute the majority of coral reef animal diversity and are believed to contribute significantly to host, community and trophic dynamics. Anilocra spp. are large conspicuous ectoparasitic isopods, making them ideal models for host–parasite studies. In the tropical western Atlantic and Caribbean, Anilocra haemuli infects the ecologically important French grunt (Haemulon flavolineatum). French grunt are trophic connectors between reef and seagrass environments, and how A. haemuli infection influences connectivity is unknown. As a first step in understanding the French grunt–A. haemuli association, we conducted reef surveys during three consecutive years to quantify the abundance and prevalence of infected fish on reef sites in the north-eastern Caribbean. We examined their correlations with fish population and aggregation size, and social affiliation. Annual infected fish abundance and prevalence per site ranged from 0–24 fish and 0–66%. Prevalence: (1) appeared autocorrelated within bays among years; (2) was inversely correlated with population and aggregation size, although the statistical significance varied; and (3) was greater for solitary than aggregating fish. Our study provides the most comprehensive dataset for prevalence of any Anilocra spp., and the necessary baseline data for future studies on Anilocra–host dynamics, and the effect of parasites on trophic and habitat connectivity.

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Nanami, Atsushi, Taku Sato, Yuuki Kawabata, and Junichi Okuyama. "Spawning aggregation of white-streaked grouperEpinephelus ongus: spatial distribution and annual variation in the fish density within a spawning ground." PeerJ 5 (February 14, 2017): e3000. http://dx.doi.org/10.7717/peerj.3000.

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White-streaked grouper (Epinephelus ongus) is an important fisheries target and forms spawning aggregations at particular spawning grounds. The aims of the present study were to investigate the ecological characteristics of annual spawning aggregations such as (1) spatial variations in the density ofE. ongusat the spawning ground, (2) the relationship between fish density and environmental variables, (3) inter-annual variations in the spawning aggregation, (4) the proportion of males to females at the spawning ground for several days pre—and post-spawning and (5) the relationship between male density and female density at the protected spawning ground, based on observations over five years at an Okinawan coral reef. Although the protected spawning ground area was large (ca. 2,500 m × 700 m), high density ofE. ongus(over 25 individuals per 100 m2) was found in a limited area (within c.a. 750 m × 50 m). Current velocity and coverage of rocks had significant positive effects on the spatial distribution ofE. ongusat the spawning ground. Inter-annual variation in the degree of aggregation was found and this variation was explained by the annual variation of mean seawater temperature during 40 days before the spawning day. The male–female ratio (male:female) at the spawning ground was ca. 3:1 for three years (May 2012, May 2014 and May 2015) whereas >13:1 for one year (May 2013). Significant positive relationships between male density and female density were found at the aggregation sites. It is suggested thatE. ongususe aggregation sites with greater current velocity to reduce the risk of egg predation and seawater temperature is one of the main factors that is responsible for determining the degree of aggregation. It is also suggested that females possibly select sites with a greater density of males and this selection behavior might be the reason why females arrived at the spawning ground after the arrival of the males. For effective management of spawning grounds, precise site selection as well as the duration of the protection period are suggested to be key aspects to protect the spawning aggregations ofE. ongus, which have been currently achieved at the spawning ground.

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Grüss, Arnaud, David M. Kaplan, and Jan Robinson. "Evaluation of the effectiveness of marine reserves for transient spawning aggregations in data-limited situations." ICES Journal of Marine Science 71, no. 3 (March 13, 2013): 435–49. http://dx.doi.org/10.1093/icesjms/fst028.

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Abstract Many coral reef fish species form predictable, transient spawning aggregations. Many aggregations are overfished, making them a target for spatial management. Here, we develop a per-recruit model to evaluate the performance of no-take marine reserves protecting transient spawning aggregations. The model consists of only 14 demographic and exploitation-related parameters. We applied the model to a protogynous grouper and a gonochoristic rabbitfish from Seychelles and tested six scenarios regarding the extent of protected areas, the level of fish spawning-site fidelity, and fishing effort redistribution post reserve implementation. Spawning aggregation reserves improve spawning-stock biomass-per-recruit and reduce the sex ratio bias in protogynous populations for all scenarios examined. However, these benefits are often small and vary among the different scenarios and as a function of sexual ontogeny. In all scenarios, increases in yield-per-recruit do not occur or are negligible. The long-term yield increases due to spawning aggregation reserves may still occur, but only if spawning-stock biomass recovery results in a recruitment subsidy. Given these limited benefits, the value of no-take reserves must be weighed against those of other management options, such as fishing effort reduction and seasonal fishery closures. The latter is particularly appropriate when spawning and non-spawning areas overlap in space.

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Parrish, Julia K. "Layering with depth in a heterospecific fish aggregation." Environmental Biology of Fishes 26, no. 2 (October 1989): 79–85. http://dx.doi.org/10.1007/bf00001024.

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Nilsson, Hel�n, Walter Steffen, and Robert E. Palazzo. "In vitro reconstitution of fish melanophore pigment aggregation." Cell Motility and the Cytoskeleton 48, no. 1 (2000): 1–10. http://dx.doi.org/10.1002/1097-0169(200101)48:1<1::aid-cm1>3.0.co;2-d.

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Chollett, Iliana, Mark Priest, Stuart Fulton, and William D. Heyman. "Should we protect extirpated fish spawning aggregation sites?" Biological Conservation 241 (January 2020): 108395. http://dx.doi.org/10.1016/j.biocon.2019.108395.

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40

Brehmer, Patrice, Erwan Josse, and Leif Nøttestad. "Evidence that whales (Balaenoptera borealis) visit drifting fish aggregating devices: do their presence affect the processes underlying fish aggregation?" Marine Ecology 33, no. 2 (August 5, 2011): 176–82. http://dx.doi.org/10.1111/j.1439-0485.2011.00478.x.

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Houwelingen, A. C. v., A. A. H. M. Hennissen, F. Verbeek-Schippersa, T. Simonsen, A. D. M. Kester, and G. Hornstra. "Effect of a Moderate Fish lntake on Platelet Aggregation in Human Platelet-Rich Plasma." Thrombosis and Haemostasis 59, no. 03 (1988): 507–13. http://dx.doi.org/10.1055/s-0038-1647525.

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SummaryThis paper describes the results of an international study to investigate the effect of a reasonable amount of dietary fish on platelet aggregation in platelet-rich plasma (PRP) induced by collagen and thrombin. In Maastricht, Tiomsø, and Zeist two groups of healthy male volunteers were given a daily dietary supplement consisting of 135 g of canned mackerel paste (experimental group, n = 40) or meat paste (control group, n = 42) for a 6-week period. Compliance, calculated on the basis of the urinary excretion of lithium, added to the supplements, was about 80%. Platelet number in PRP decreased significantly in the fish group. Collagen-induced platelet aggregation in PRP differed widely between the three centres despite the attempt to use exactly the same conditions. Nonetheless, aggregation decreased significantly in the fish group. The mackerel effect on thrombin-induced aggregation was inconsistent.

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42

Doray, Mathieu, Pierre Petitgas, and Erwan Josse. "A geostatistical method for assessing biomassof tuna aggregations around moored fish aggregating devices with star acoustic surveys." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 6 (June 2008): 1193–205. http://dx.doi.org/10.1139/f08-050.

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Universal kriging was used to model the spatio-temporal variability in the acoustic density of tuna aggregations recorded during star echosounding surveys around moored fish aggregating devices (FADs) in Martinique (Lesser Antilles). The large-scale deterministic drift in the tuna spatial distribution was modeled using an advection–diffusion equation applied to animal grouping. Residuals from the drift were modeled as a random component with small-scale spatial correlation. An estimation variance formula was derived from this deterministic–statistical mixed model to assess the mean precision of density estimates of daytime tuna aggregation. The mean relative error obtained with our star design for daytime surveys was 24%. The methodology was applied to estimate daily maxima of tuna biomass around moored FADs during four monthly sea cruises. The daily peak of tuna biomass aggregated around moored FADs was 9 t on average (standard deviation = 4). Estimation variances for different survey designs were compared for optimizing sampling strategy.

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Elliott, NG, and RJ Kloser. "Use of acoustics to assess a small aggregation of orange roughy, Hoplostethus atlanticus (Collett), off the eastern coast of Tasmania." Marine and Freshwater Research 44, no. 3 (1993): 473. http://dx.doi.org/10.1071/mf9930473.

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A relatively small aggregation of orange roughy (Hoplostethus atlancticus) was located in April 1989 off the eastern coast of Tasmania. A Simrad EK400 (38 kHz) scientific echo-sounder was used to survey the aggregation over a period of eight days, during which time the aggregation was commercially fished. The aggregation was confined to an area of approximately 4 km2, with the dimensions of the aggregation varying within and between days. High densities of orange roughy were located near the bottom on some days and more than 24 m off the bottom on others. Average fish densities during the survey and an estimate of the extremes of densities (fish m-3) are presented. Estimates of the original biomass of this aggregation as obtained from acoustic data and commercial catch-and-effort data are compared, and the mean target strength of the population is estimated.

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Doray, Mathieu, Pierre Petitgas, Laetitia Nelson, Stéphanie Mahévas, Erwan Josse, and Lionel Reynal. "The influence of the environment on the variability of monthly tuna biomass around a moored, fish-aggregating device." ICES Journal of Marine Science 66, no. 6 (March 11, 2009): 1410–16. http://dx.doi.org/10.1093/icesjms/fsp039.

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Abstract Doray, M., Petitgas, P., Nelson, L., Mahévas, S., Josse, E., and Reynal, L. 2009. The influence of the environment on the variability of monthly tuna biomass around a moored, fish-aggregating device. – ICES Journal of Marine Science, 66: 1410–1416. Fish-aggregating devices (FADs) are increasingly used worldwide to enhance tuna catches. Meanwhile, ecosystem-based management of this fishery is constrained by a paucity of information regarding the interaction of FAD-associated tuna aggregations with their local environment. This paper reports the results of a nine-month study around a FAD moored near Martinique Island, aimed at assessing the effects of the local environment on the variability of monthly estimates of proximate tuna biomass. Dual-frequency, active acoustics provided high-resolution quantitative data on the pelagic community around the FAD, from fish to micronekton forage. Geostatistics were used to compute biomass estimates of the tuna aggregation comprising most of the FAD-associated fish biomass, with a sampling error of 27%. Environmental variability was summarized by a small set of principal components (PCs) derived from profiles of temperature, salinity, and dissolved oxygen vs. depth; and maps of chlorophyll a derived from remotely sensed, sea surface colour. A generalized linear model was used to relate tuna biomass to environmental PCs and revealed a positive correlation between tuna abundance and: (i) a micronekton layer sensed at 38 kHz and potentially consisting of preferred prey at ∼180-m depth; and (ii) low subsurface salinity (60–80 m). These favourable environmental conditions may be related to the presence of North Brazilian Current eddies that migrating tuna follow when not temporally associated with the FADs.

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MARQUES, J. F., M. J. SANTOS, and H. N. CABRAL. "Aggregation patterns of macroendoparasites in phylogenetically related fish hosts." Parasitology 137, no. 11 (May 26, 2010): 1671–80. http://dx.doi.org/10.1017/s0031182010000491.

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SUMMARYMacroparasites are generally aggregated within their hosts with infection and aggregation levels resulting from a continuous arms race between maintaining high mating probability and host mortality low for which host and environmentally related factors contribute to some extent. Here, infection and aggregation patterns of the macroendoparasites infecting the flatfish Citharus linguatula, Arnoglossus laterna, Lepidorhombus boscii, Scophthalmus rhombus and Platichthys flesus in 3 areas along the Portuguese coast were analysed. Of the 21 macroendoparasite species found only 1 infected all hosts and most were host or area exclusive. For each host-parasite system, values of the indices varied between areas and macroendoparasites were not always aggregated; in fact, some macroendoparasites were generally uniformly distributed, which can be related to specific density-dependent regulation mechanisms. No general pattern was found for infection or aggregation levels of the 3 species infecting more than 2 hosts along the Portuguese coast, i.e. Lecithochirium rufoviride, Nybelinia lingualis and Anisakis simplex s.l., suggesting that regulation mechanisms are not species specific but are locally determined, with host ecology playing a significant role.

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Matsubara, Yuhei, Tetsuo Wakamatsu, and Hideaki Noda. "Study on Behavior of Fish School Around Aggregation Devices." PROCEEDINGS OF CIVIL ENGINEERING IN THE OCEAN 11 (1995): 133–38. http://dx.doi.org/10.2208/prooe.11.133.

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Cameron, Katherine, Brice Semmens, Christy V. Pattengill-Semmens, Steve Gittings, Croy McCoy, and Ana Širović. "Acoustic competition of Serranids at a fish spawning aggregation." Journal of the Acoustical Society of America 141, no. 5 (May 2017): 3944. http://dx.doi.org/10.1121/1.4988941.

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Dempster, T., and MJ Kingsford. "Homing of pelagic fish to fish aggregation devices (FADs): the role of sensory cues." Marine Ecology Progress Series 258 (2003): 213–22. http://dx.doi.org/10.3354/meps258213.

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Dempster, T. "Temporal variability of pelagic fish assemblages around fish aggregation devices: biological and physical influences." Journal of Fish Biology 66, no. 5 (May 2005): 1237–60. http://dx.doi.org/10.1111/j.0022-1112.2005.00674.x.

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Karlsson, Jan Olof G., Nils Grundstrom, Hans Elwing, and Rolf G. G. Andersson. "The Fish Pigment Cell: An Alternative Model in Biomedical Research." Alternatives to Laboratory Animals 18, no. 1_part_1 (November 1990): 201–24. http://dx.doi.org/10.1177/026119299001800121.1.

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Receptor-mediated pigment aggregation within pigment cells (chromatophores) of an isolated fish scale is an ideal model system for functional receptor studies. The superficial layer of the scale contains both dermal chromatophores and postganglionic sympathetic nerves. By means of stimulation of the nerves, or by addition of appropriate receptor agonists, it is possible to elicit pigment aggregation within the chromatophores. A single fish can contribute hundreds of scales, various pharmacological and biochemical experiments are easily carried out and the physiological response, i.e. pigment aggregation, is readily evaluated by the aid of a light microscope or a simple scale photometer. A denervation model, based on isolated scales, permits studies of factors involved in the sensitivity change, which typically takes place after experimental or pathological denervation. By using isolated fish scales it is quite simple to illustrate many biomedically important concepts, like receptor theory and nerve-effector cell communication. This makes the scale a very useful preparation in biomedical education.

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Journal articles on the topic 'Fish aggregation'

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