Fish Attraction Research Articles

Attraction of Wild Coastal Fishes to an Atlantic Subtropical Cage Fish Farms, Gran Canaria, Canary Islands

We assessed the influence of two commercial fish farms on the local aggregation of coastal wild fishes through a 'post-impact' sampling design at Gran Canaria Island (Canary Islands). At each farm, we established two controls and one impact location and estimated fish abundance bimonthly by means of SCUBA diving. Results provide evidence of local aggregation in the associated fish assemblages around sea-cage fish farms. Dissimilarities between control and impact locations for both fish farms were due to differences on the abundance of a few species. However, we detected significant differences by means of some assemblages between controls in one fish farm, as a consequence of the removal and re-location of cages. Moreover, we also detected significant within location small-scale variability for several fish assemblages around both sea-cages farms. Otherwise, we did not observe any effect of sampling times.

Downstream migration in Atlantic salmon (Salmo salar) smolt sibling groups

Previous studies have shown kin recognition abilities in salmonid fish. Some authors have suggested that the attraction of juvenile fish to siblings may indicate preference for shoaling with kin. The aim of the present study is to test the prerequisite for the hypothesis that siblings swim spatially closer than unrelated fish during their seaward migration as smolts. Atlantic salmon (Salmo salar) eggs from three families were each reared in two tanks to create familiar and unfamiliar sibling smolts. Before the experiment started they were tagged individually withpassive integrated transponders (PITs). Twelve individuals from each of six groups were mixed and released together at several occasions in the upper end of the 400-m-long experimental stream. An automatic PIT-monitoring system placed in the outlet recorded the time for passage of each individual leaving the stream. Eighty-five percent of the juveniles monitored by the PIT antenna showed downstream migration at night hours and they migrated significantly more often closer in time to both known and unknown siblings than to unrelated fish. The results suggest that there is a genetic component in the migratory behaviour of Atlantic salmon smolts and support the hypothesis that smolts migrate in kin-structured groups.

Attraction of settlement-stage coral reef fishes to reef noise

We compared catches of settlement-stage reef fishes in light traps attached to under- water speakers playing reef sounds with those of silent traps during a summer recruitment season at Lizard Island, Great Barrier Reef, Australia. Of the total 40191 reef fishes we collected, significantly more (67%; Wilcoxon and Binomial tests: p< 0.001) appeared in the traps with broadcast reef noise. Traps deployed with speakers consistently caught a greater diversity of species (Wilcoxon test: p< 0.001, total 81 vs 68) than did silent traps. This study provides a clear demonstration that the settlement-stages of a broad range of families of coral reef fishes are attracted to reef sounds.

Unexpected large numbers of Mullus suvmuletus juveniles in open waters of the Mediterranean sampled with light attraction devices

Experimental night hauls with a purse‐seine were performed using two light devices in waters off Majorca in the western Mediterranean to investigate light attraction of juvenile fishes in epipelagic waters over the continental slope. Large numbers of Mullus surmuletus were caught indicating that light devices are suitable for sampling juveniles (2–6 cm) of this species. The data obtained can be used to provide valuable information on geographic distribution and spatial aggregation patterns of this mullid, altogether with the acquisition of biological samples for growth or stomach contents analyses of juveniles stages.

An alternative to dolphin oil as a fish attractant in the Ganges River system: conservation of the Ganges River dolphin

Oil extracted from blubber of the Ganges River dolphin, Platanista gangetica, is used as a fish attractant in India and Bangladesh. This oil fishery is associated with the mortality of hundreds of dolphins every year. Oil from fish scraps was field tested for 121 days during 1997–1999 in the Ganges at Patna and was a very effective alternative to dolphin oil as a fish attractant. Fishing with fish oil resulted in higher catches and greater income per person per hour (Rs. 17.8±12.5) than fishing with dolphin oil (Rs. 11.6±9.3). However, there is no statistically significant difference between the results from fishing with dolphin and fish oil. Oil from fish scraps is inexpensive and can be made readily available to all the fishermen. Its widespread use would help in conserving the endangered Ganges River dolphin.

Attraction of wild fish to sea-cage fish farms in the south-western Mediterranean Sea: spatial and short-term temporal variability

Aggregations of wild fish were counted around 9 floating sea-cage fish farms along a 300 km stretch of the Spanish coastline in the south-western Mediterranean Sea. Each fish farm cul- tivated Sparus aurata and Dicentrarchus labrax in 6 to 16 floating sea cages between 10 m and 7.4 km from the coast. During September and October 2001, assemblages of fish were counted on 3 separate days at each of 9 farms. Six 5 min rapid visual counts using SCUBA and covering 11 250 m 3 were per- formed within each farm complex and at open water control sites 200 m distant from farms. Abun- dance (52 to 2837× ), biomass (2.8 to 1126 × ) and number of species (1.6 to 14 × ) were greater in fish farm counts than control counts at all locations. Twenty-seven species were recorded at fish farms, with 2 families, Sparidae (12 species) and Carangidae (4 species), being particularly abundant. Over 85% of farm-associated fish were of adult size. Assemblages of wild fish differed greatly between farms separated by 10s to 100s of km, although there was some evidence to suggest that similar assemblages occur at farms separated by 100s of m to several km. Abundance, biomass and number of species differed among fish farms, with all 3 variables negatively correlated with distance of farms from shore and positively correlated with size of farms. Limited variability of wild fish assemblages and abundance of the dominant taxa at each farm among times sampled indicated some degree of temporal stability on a scale of several weeks. Due to the strong aggregative effect of fish farms, pos- sible residence of fishes for periods of weeks to months and the prohibition of fishing within farm leasehold areas, we suggest that coastal sea-cage fish farms may act as small (up to 160 000 m 2 ), pelagic marine protected areas (MPAs). Furthermore, at farms where wild fish are abundant, ecolog- ical interactions that may influence both wild fish stocks and the impact of farms must be considered.

Potencial atrator de peixes ósseos em recife artificial no litoral norte do estado do Rio de Janeiro, Brasil

Artificial reefs have been used in many countries to increase coastal fishery productivity. In order to increase fish attraction to the Northern Coast of Rio de Janeiro State, it was installed an artificial reef (1,500 m2) 5 nautical miles off Manguinhos's Bay (Sao Francisco de ltabapoana, Rio de Janeiro). The artificial structures were made of tires, concrete and cement blocks. A gill net of 125 x 3 m was monthly used in the artificial reef (AR) and in a control area (CA) to determine the effect of the experimental structures on the stock and diversity of coastal sharks. Considering the complexity of a sustainable elasmobranch exploitation, sharks were focused in this study. During 24 months of investigation (April/96 to March/98), a total of 325 individuais distributed in four shark species were captured in the two areas (AR and CA): Mustelus higmani (Springer & Lowe, 1963) (AR = 70; CA = 82 individuals), Rhizoprionodon lalandii (Valenciennes, 1839) (AR = 86; CA = 56 individuals), R. porosus (Poey, 1861) (AR = 16; CA = 14 individuals) and Carcharhinus brachyurus (Gunther, 1870) (AR = 1 individual). The attractive potential of the artificial reef is suggested by the predominance of the shark R. lalandii in the reef complex after the first year of monitoring, with the increase of the structures.

Fishway entrance modifications enhance fish attraction

Two Denil fishways on the Grand River, Ontario, were monitored annually since 1994 for activity by several dozen fish species. Fishway entrances were enlarged and repositioned approximately 2 m closer to the weir face, in areas where fish were attracted by weir discharge. These simple modifications resulted in increased attraction efficiency for pumpkinseed, Lepomis gibbosus (L.). After modifications, annual relative rate of recapture was 39% (95% confidence interval [CI]=32–46%), representing a 2.6–3‐fold increase in fishway use relative to pre‐modification conditions. Median daily recapture rates also increased significantly from 0% at both fishways to approximately 2%. These results suggest that fishway entrances should be located as close to a dam or weir face as possible, but velocity barriers from spillway or tailrace discharge must not compromise access.

The ecology of and fishery for &lt;i&gt;Coryphaena&lt;/i&gt; spp. in the waters around Australia and New Zealand

Two species of dolphinfish, Coryphaena hippurus and Coryphaena equiselis, are found in Australian waters and off the north-eastern coast of New Zealand. Both species (also called Mahi-mahi, or dorado) are generally found in tropical waters, but only C. hippurus is captured in southern waters (to 34°S). Dolphinfish are caught by recreational and commercial fishers, using either trolled or baited lines. Most catch records do not allow the identification of fish to the species level. Dolphinfish are also an incidental catch of foreign and domestic pelagic fisheries (e.g. long-lining for tunas and billfishes) and 10-70 tonnes are taken per year in the Australia-New Zealand region. Although Coryphaena are known to associate with objects (e.g. traps for carangids and navigation buoys) and are a focus for recreational fishers, Fish Attraction Devices (FADs) are not used by commercial fishers off the coast of Australia and New Zealand. FADs are, however, used by fishers in the Pacific Islands. Recreational catches of Coryphaena may exceed the commercial catch in some areas. Good data for New South Wales, Australia, gave estimates of 11.7 and 12.7 tonnes of Coryphaena caught in 1994 and 1995 respectively, which represented 1.1-1.8x the recorded commercial catch. Approximately ~12,600 fish have been tagged since 1973 around Australia and data on returns are only available for 108 fish (0.86% recovery). Tagged Coryphaena were found to move distances of up to 440 kilometres and at estimated speeds of up to 20 kilometres per day. The time between tag and recapture varied from 0-360 days and fish moved 0-440 kilometres. The majority of fish were caught around the same drifting object near where they were tagged. The collection of Coryphaena larvae in Queensland and New South Wales, along the east coast of Australia, indicates spawning in these waters. Most larvae have been collected in the austral summer and autumn and typically in surface waters well offshore. Dolphinfish have been successfully raised from eggs to fish of marketable size in Western Australia and the species appears to be an excellent candidate for mass production, which is now possible in Australia.

Fish Attraction Devices (FADs) and experimental designs

There is widespread use of fish attraction devices (FADs) in commercial fisheries and research. Investigations on the utility of FADs to catch fishes, and factors influencing fishes associated with FADs, require careful consideration of experimental designs. The development of appropriate models, from observations and the literature, should be developed before hypotheses can be tested with robust sampling designs. Robust sampling designs may only be possible if investigators have some role in the planning stage of deploying FADs. If the objective of the study is to determine the influence of FADs on assemblages of fishes, then experimenters need to consider that a `FAD-effect´ (=impact) cannot be demonstrated without controls. Some preliminary studies may be required to determine the spatial extent of a FAD-effect before suitable sites can be chosen for controls. Other controls may also be necessary, depending on the method used to estimate numbers of fishes (e.g. controls for disturbance). Recent advances in sampling designs that are applicable to impact studies are discussed. Beyond-BACI (Before After Control Impact) and MBACI (Multiple BACI) designs are recommended because they cater for temporal and spatial variation in the abundance of organisms, which is generally great for pelagic fishes. The utility of orthogonal sampling designs is emphasised as a means of elucidating the influence of multiple factors and, importantly, interactions between them. Further, nested analyses are suggested to deal with multiple temporal and/or spatial time scales in sampling designs. The independence of replicate FADs should also be considered. Problems of independence include: FADs that are connected, thus providing potential routes of movement of associated fishes; temporal dependence where the number of fish at a time influences the number at the next time due to fish becoming residents; and the fact that the proximity of other FADs may influence numbers of fishes. Solutions to these problems are suggested. The recommendations in this paper are relevant to investigations on pelagic fish of all sizes, with and without FADs.

An assessment of the use of stabilized coal and oil ash for construction of artificial fishing reefs: Comparison of fishes observed on small ash and concrete reefs

Fishes present on small artificial reefs located 2 km off the central east coast of Florida (USA) were surveyed to determine the acceptability of using stabilized oil and coal ash residue as a component material in construction of artificial fishing reefs. Species richness was not significantly different over 2.5 yr on stabilized oil and coal ash reefs compared to concrete control reefs. Of 19 species tested for significant differences in mean abundance, lane snapper was observed at significantly higher mean abundances on fossil-fuel ash reefs (stabilized oil ash/coal fly ash), while three reef species (hairy blenny, porkfish and gray snapper) were significantly more common on concrete control reefs. Further study is needed to determine whether contaminants (Cu, V, Ni and Zn) from stabilized ash blocks can cause abundance differences for some fishes. Plausible alternate explanations for the differences in mean abundance include both interspecific interactions (competition and predation) and differences in the attraction or retention of fish among reef replicates due to slight variations in reef dimensions.

The relationship between numbers of fish attracted to baited cameras and population density: Studies on demersal grenadiers Coryphaenoides (Nematonurus) armatus in the abyssal NE Atlantic Ocean

The number of Coryphaenoides (Nematonurus) armatus attracted to baits ( N peak) at depths of 2000–5000 m in the NE Atlantic Ocean is shown to vary with fish density ( n km −2) in accordance with the equation: N peak = dn x (1− exp((−c exp(−nk)−m)x)) where c=350, d=4.095×10 −3, k=0.0037, m=10, x=0.005 which predicts a dome-shaped relationship with a maximum number observed at intermediate population densities. This results from more rapid arrival of fish at high densities being offset by shorter staying times in the food-rich environment of high-density localities. Caution is advised when using attraction of fish to baited cameras as an index of stock abundance.

Management of size variation in juvenile gilthead sea bream ( Sparus aurata). I: Particle size and frequency of feeding dry and live food

The effects of particle size and frequency of feeding on survival, growth and growth depensation of juvenile gilthead sea bream were investigated in three separate experiments. In the first experiment the effects of dry food particle size and frequency of feeding were investigated with all treatments being equally supplemented with Artemia. Growth depensation, measured as the change in the coefficient of variation of mean weight (ΔCV), was affected by particle size but not by frequency of feeding. Frequency of feeding did, however, have a significant effect on growth rate. In the second experiment the effects of feeding brine shrimp, Artemia, as a supplemental feed were tested. Feeding continuously with brine shrimp resulted in a lower ΔCV than periodic feeding (ΔCV values of 15.6 vs. 21.8%, respectively). In the third experiment the effect of feeding Artemia as the sole source of food was tested. Continuous feeding resulted in a seven-fold higher ΔCV as compared to periodic feeding (ΔCV values of 24.6 vs. 3.6%, respectively). Competitive interactions between individuals of different size, and the differential attraction of fish to dry pellets and live food, are discussed as possible behavioral mechanisms underlying the results. Careful management of food administration (i.e. feeding frequency and particle size) could reduce the need for labor-intensive and stressful size-grading during nursing.

Ratios of expected values (REX), a method for impact evaluation of thermal discharges on the fish community in the Pickering littoral waters of Lake Ontario

Discharge effects on the fish community are assessed for the Pickering power station and a creek in the neighbourhood, located in littoral waters of the northern shore of Lake Ontario. Since the ambience is cold in spring and fall, when the main spawning migration takes place, any positive thermal variation is selected with preference by the onshore migrants. Our goal is to identify these effects when significant or, alternatively, the community richness reduction, and even the biological damage to fish. Ratio to Expected Values (REX) involves a comparison of the diversity indexes from locations under impact versus ambient samples, in order to identify the effect magnitude. To clear the background records of local effects, they were checked for outliers, which have been replaced based on missing-value techniques. Applying the method, the slight thermal increase of the creek discharge was found to produce a higher richness compared to station discharges, hence offering more attraction for onshore migrants. Despite the high attraction of station thermal plumes, the general result is negative, due to a process described here as ambiguous attraction. It is preliminarily identified as a fish attraction, due to favourable thermal conditions at the plume edges, followed by repulsion and fish exhaustion, due to low oxygen level and absence of spawning conditions for the attracted fish, further in the plume. The paper also introduces a new statistical approach of effect evaluation for significance, based on pair comparison of records in the suspected area versus background records.

Importance of fish aggregating devices (FADs) as substrates for food organisms of fish

Various hypothesis have been proposed to explain why floating artificial habitats are successful in attracting fishes. Food may be a stimulus for aggregating some species around Fish Aggregating Devices (FADs). This study attempts to discover if sessile marine organisms which readily encrust traditional FADs, are important food organisms for fish. A new group of FADs was installed in a rich fishing ground. Different parts of the FADs were sampled every 2 weeks for identification of encrusted organisms, and ten species were identified. The density of the organisms fluctuated with time of immersion. Plankton collected from the water at the FAD sites was also identified. Stomach contents of 90 fishes caught around these FADs were analyzed and the organisms found in the stomachs were compared with those on the FADs. This study suggests that the attraction of fishes to FADs is due to mechanisms other than feeding on organisms encrusting the FADs.

Comparisons of Three Manufactured Artificial Reef Units in Onslow Bay, North Carolina

Abstract Three types of benthic artificial reef units were tested by the North Carolina Division of Marine Fisheries Artificial Reef Program: steel cubes, fiberglass-covered plastic domes, and concrete pipes. Evaluations were conducted in 1990 and 1991 at two sites in Onslow Bay, North Carolina. Reef materials were compared at the deep site (≥15 m) by quantifying stability, durability, target fish attraction, and cost per unit surface area. Assessment at the shallow site (<15 m) included only stability, durability, and cost per unit surface area. Cubes and domes were stable in shallow (<15 m) waters. Pipes and domes were stable and cubes were unstable in deep waters (≥15 m). Pipes were evaluated only at the deep site, The only structural damage observed was to two domes which were crushed during deployment. Acceptable postdeployment durability was observed for all three materials through 2 years of monitoring. Relative abundance and species richness for target fishes were assessed at the deep site and wer...

The use of sodium dodecyl sulphate-polyacrylamide gel electrophoresis to confirm the presence of salmon (Salmo salar) eggs in an illegal fish bait.

AbstractSalmon roe was identified as the major component of a suspected illegal fish attractant using sodium dodecyl sulphate‐polyacrylamide gel electrophoresis to analyse protein extracts prepared from various salmonid eggs and a suspected illegal bait.

Panfish Use of and Angler Success at Evergreen Tree, Brush, and Stake-Bed Structures

Abstract The material selected for artificial structures is usually determined by availability or by the preference of a sponsoring organization. Comparative studies of panfish use of different structure materials and types have been inconclusive, largely because of confounding effects of depth, location within a reservoir, or difference in fish populations. We evaluated the utility of several materials and types in a localized area of an Ohio reservoir. The materials consisted of vertical and prone evergreen trees, a brush pile, and stake beds with 150-mm and 350-mm spacing. Utility was based on fish attraction (determined by pop-net sampling), angler success (determined by controlled angling), and cost ofeach material. Evergreen trees yielded pop-net catches ofbluegills Lepomis macrochirus that were equal to or significantly greater than catches at the other structures. Catches of white crappies Pomoxis annularis were not significantly different between materials during pop-net sampling. Anglers enjoyed...

Evaluation of a Hidrostal Pump Fish Return System

Abstract We tested the effectiveness of a Hidrostal pump and filtered mercury vapor light system for attracting, concentrating, and transporting fish commonly impinged on water intake structures of thermal electric generating stations on the Great Lakes. In general, the Hidrostal pump effectively transported test fish with relatively low mortality rates. Mortality varied among fish species, with rainbow trout (Salmo gairdneri) significantly hardier than yellow perch (Perca fiavescens) and alewife (Alosa pseudoharengus). Mortality also generally increased at higher pumping speeds, while mortality of yellow perch was greater in a long transport loop than in a short transport loop. In tests of fish attraction and capture, the addition of a filtered mercury vapor light significantly increased the efficiency of fish capture of the Hidrostal pump transport system. Other directive cues (bubble curtains, strobe lights, and electric fields) did not significantly improve the efficiency of the Hidrostal pump-mercury...

Attraction of Fish to Mercury Vapour Light and Its Application in a Generating Station Forebay

AbstractLaboratory and field tests were conducted to determine the effectiveness of filtered mercury vapour lights in attracting fish with possible utilization in a fish conserving scheme at an electrical generating station. In laboratory tests, alewife demonstrated an attraction to the mercury vapour light which was associated with an increase in swimming activity. This response was maintained over a 48‐hour period. When the filtered mercury vapour lights were utilized in association with a fish pump in the Nanticoke Generating Station forebay, juvenile gizzard shad and smelt were attracted to the pump area. Although there was variation with time of day, tubidity and lighting array; the results suggested that the number of fish passing through the pump increased when the mercury vapour lights alone or when the mercury lights in association with a white strobe light were employed.