Common Predatory Fish Research Articles

The Results of Introduction of the Pike-Perch, Sander lucioperca, into Lake Khanka

As reported in the 1930s, the level of the forage base in Lake Khanka could provide from 2600 to 17 000 t of fish. The low fish capacity of the lake was explained mainly by a high abundance of small non-commercial species. For the purpose of increasing the fish capacity, a proposal was made in 1961 to introduce the Pike-Perch into Lake Khanka. This fish was expected to provide 200–300 tons extra fish product a year and also increase the proportion of valuable fish species in the lake by “destroying harmful rough fish” within 10–12 years. The introduction of pike-perch into Lake Khanka was carried out in 1970–1978. An analysis of data on the current status of the pike-perch population in the lake shows that this species has formed a stable self-reproducing population, whose biomass is now comparable to the level of the native common predatory fishes (80–100 t). In preying mainly on the sharpbelly (genus Hemiculter) and other abundant rough fish, it does not compete with other predators. Nevertheless, the pike-perch provides 20 t of marketable product a year, being rated as the second or third most commercially valuable fish species in catches from the lake.

Human use of small forage fish: Improved ancient DNA species identification techniques reveal long term record of sustainable mass harvesting of smelt fishery in the northeast Pacific Rim

The bulk storage and mass capture of small forage fish has played a primary role in the cultural traditions and subsistence practices of many ancient and modern indigenous communities throughout the world. Archaeologists are improving their recognition of human interaction with these fisheries through the application of fine-mesh screening techniques and ichthyofaunal analysis of fish bone. Because of the differing life histories of many of these fish, determining their species from archaeological contexts can improve our resolution of past harvesting and consumption patterns. This has remained a challenge for many categories of fish, such as salmon and smelt. Here, we present an improved genetic species identification process that utilizes ancient DNA amplification techniques involving a reagent-rich PCR protocol (i.e., “Rescue PCR”) and a PCR Enhancer Cocktail P (i.e., PEC-P) to identify smelt and other forage fish bone from five archaeological sites located along the northern California (United States) Pacific coast dating to the Late Period (after 1300 cal BP). Through the application of these novel techniques, our species identification success rate increased to 71.2% overall, with some sites having a remarkable 100% success rate. We identified the species of 104 of 146 fish vertebrae, and determined that inhabitants at these sites harvested primarily surf smelt with potentially less emphasis on night smelt. Observations of herring, perch, sculpin and rainbow trout/steelhead were also made. Along with these small surf fish, we found evidence of larger fish such as shark and Pacific hake (common predatory fish in the area). The study demonstrates a significant breakthrough in ancient DNA identification techniques that resulted in information that speak to the long term continuity of use of mass harvested forage fish by indigenous peoples. The results of this project help establish a better understanding of subsistence and cultural traditions of northern California indigenous communities, with the potential to provide a more global understanding of fishing technologies, sustainability, and mass harvesting of small fishes.

Dynamic trophic linkages in a large estuarine system — support for supply-driven dietary changes using delta generalized additive mixed models

Trophic dynamics within aquatic systems are a predominant regulator of fish production and an important consideration for implementing ecosystem approaches to fisheries management. We analyzed 10 years of fish diet data from Chesapeake Bay, USA, to (1) evaluate the effects of environmental variables on trophic interactions of 12 common predatory fishes, (2) infer dynamics of four key prey groups (mysids, bay anchovy, bivalves, and polychaetes), and (3) evaluate whether interannual dietary trends were coherent among predators and regulated by prey availability. Based on delta generalized additive mixed models (delta-GAMMs), predator length was the most important covariate in modeling prey consumption. When latitude, temperature, and depth effects were statistically significant, the effects of each variable were largely similar across predators for a given prey. Annual patterns of mysid and bivalve consumption each showed a single, dramatic peak shared by multiple predators with varied feeding preferences and distributional characteristics, but annual trends were not correlated with available survey-based measures of prey availability, likely due to methodological differences. Overall, the coherence in consumption patterns across predators was consistent with supply-driven dynamics controlled by regional and annual changes in prey availability. Also, the novel application of delta-GAMMs to fish diet data was useful in characterizing the dynamics of poorly sampled prey groups and the trophic interactions for ubiquitous species from the Northwest Atlantic Ocean.

Trophic status and trophic interactions of common predatory fish species of the West Kamchatka shelf

Feeding and trophic relationships have been studied for the common benthic predatory fish species of the West Kamchatka shelf in 2008—the Pacific cod Gadus macrocephalus, great sculpin Myoxocephalus polyacanthocephalus, plain sculpin M. jaok, sea raven Hemitripterus villosus, and whitespotted greenling Hexagrammos stelleri. Crustaceans and fish are the main food components of the great sculpin, plain sculpin, Pacific cod, and whitespotted greenling; sea raven feeds on the fish mostly. The ontogenetic changes of the food spectra have been tracked for all the studied species. The indexes of the food similarity evidence to the possible food competition between the Pacific cod and all the other species; however, the dissimilarity of the ecological niches may serve as the adaptation to decrease the food competition. The trophic levels of all the studied predators vary from 3.41–4.50; i.e., they are the tertiary consumers. It is justified that the Pacific cod, whitespotted greenling, plain sculpin, and great sculpin are the facultative polyphagous predators, and the sea raven is the obligate bentho- and ichthyophagous species on the West Kamchatka shelf.

Top-down trophic shifts in Florida Keys patch reef marine protected areas

ABSTRACT: Special Protected Areas (SPAs) were established within the Florida Keys NationalMarine Sanctuary in 1997 to address a variety of management goals including coral reef resourceprotection and recovery. Within these areas all consumptive activities are prohibited. To evaluatewhether SPA establishment has resulted in reef assemblage differences on inshore patch reefs, wequantified reef fish abundance and biomass, grazing intensity and benthic cover on abiotically simi-lar protected and reference reefs. Transect surveys indicated that biomass and mean body lengths forseveral common predatory fish species were significantly greater within SPAs. Size classes of herbiv-orous fish also varied with protection; adult herbivorous fish were significantly more abundant, whilejuveniles were significantly less abundant within SPAs. Grazing intensity and benthic cover weresite-specific and did not vary consistently with protection, suggesting that SPA establishment has notimmediately (within 10 yr) driven observable indirect effects on the benthos.KEY WORDS: Marine reserve · Coral reef · Florida Keys · Trophic cascade · Parrotfish · Herbivory

Piscicidal and anti-acetylcholinesterase activity of Euphorbia royleana stem bark extracts against freshwater common predatory fish Channa punctatus

The present paper deals with the piscicidal activity of different solvent extracts of Euphorbia royleana stem bark against freshwater predatory fish Channa punctatus, which is commonly present in shrimp and carp culture ponds. The rank of order of toxicity of different solvent extract was: diethyl ether (LC 50 (96 h) 31.76 mg DW/L) > chloroform (LC 50 (96 h) 56.26 mg DW/L) > methanol (LC 50 (96 h) 56.80 mg DW/L) > acetone (LC 50 (96 h) 65.77 mg DW/L). There was a significant ( P < 0.05) negative correlation between LC values and exposure periods, thus increase in exposure time. The LC 50 values of diethyl ether extract of E. royleana stem bark decrease from 81.78 mg DW/L (24 h) to 31.76 mg DW/L (96 h). Similar trend were also observed in case of chloroform, methanol and acetone extracts. Exposure of sub-lethal doses (40% and 80% of LC 50) of the diethyl ether extract for 24 h or 96 h caused significant inhibition in the activity of enzyme acetylcholinesterase (AChE) in liver and muscle tissue of fish C. punctatus. There was a significant recovery observed in the activity of enzyme acetylcholinesterase in both the tissues of fish after 7th day of the withdrawal of treatment. Thus, the diethyl ether extract of E. royleana stem bark can be used for control of unwanted predatory fish C. punctatus from fish culture ponds. Their toxicological action is due to their anti-acetylcholinesterase enzyme activity, reversibility in their action is advantageous factor for their use as environmentally safe piscicide in aquatic bodies.

Trophic cascading effects of predatory fish on leaf litter processing in a Japanese stream

A manipulative field experiment to test for trophic cascading effects of predatory fish on detritus processing by benthic invertebrates was performed in stream channels running through a wetland forest in northern Japan. To control for fish effects on benthic invertebrates, two simple treatments (fish‐present and fish‐absent) were established for 4 weeks, with two common predatory fish, rainbow trout (Oncorhynchus mykiss) and freshwater sculpin (Cottus nozawae), being introduced into and excluded from stream cages. At the end of experiment, the biomass of the dominant detritivore, an amphipod (Jesogammarus jezoensis), was significantly less in the fish‐present treatment (0.56 g m–2 in dry mass on average) than that in the fish‐absent treatment (1.32 g m–2), there being no significant treatment effect evident for the second‐dominant detritivore, coleopteran larvae (Optioservus kubotai). The loss of oak leaves (Quercus crispla) from litter bags in the fish‐present treatment (0.31 g week−1 in dry mass on average) was significantly less than in the fish‐absent treatment (0.54 g week−1). Predator‐induced lower biomass and likely lowered foraging activities of the J. jezoensis were responsible for the suppression of litter processing efficiency. In contrast, the standing crop of fine particulate organic matter did not differ significantly between the treatments. The experimental results revealed that the predatory fish had an indirect but significant effect on leaf litter processing in the stream.

Does tethering of mobile prey measure relative predation potential? An empirical test using mummichogs and grass shrimp

Tethering prey organisms continues to be a popular method of evaluating spatial and temporal variation of predator effects on population or community dynamics in marine environments. However, this technique relies on an untested fundamental assumption that there is a simple, reliable relationship between losses of tethered prey and site-specific risk of mortality due to predation. To test this, we placed tethered and free grass shrimp Palaemonetes pugio together in mesocosms (1.3 m diameter) and varied the level of predation potential by exposing the prey to different densities of the mummichog Fundulus heteroclitus, a common predatory fish in salt marshes of the eastern US. There were 10 replicate experimental runs, each involving 6 mesocosms that included 3 tethered and 27 free shrimp and either 0, 1, 2, 4, 8, or 16 predators. Survival of tethered shrimp was assessed after 15, 30, 45, 60, 90, 120 and 180 min, but survival of free shrimp was determined only at the end of each run (180 min). In the absence of predators, average survival of tethered (93.3%) and free (99.3%) shrimp was similar. At the highest predator density, none of the tethered shrimp survived to 180 min, while survival in the free group was 85.1%. A significant interaction (ANOVA, F 5,108 = 11.88, p < 0.0001) between tether treatment and predator density indicated a difference in the slopes of the relationships describing survival of free and tethered prey across the experimental gradient of predation potential, Chronological analysis of tethered prey losses across the experimental predation gradient also detected significant interactions (repeated-measures ANOVA, F30 324 = 3.24, p < 0.001) between the effects of predator density and exposure time. Tethering grass shrimp as a means of assessing even relative effects of predation by mummichogs on free prey is of questionable value because the relationship between relative loss rates of tethered and free shrimp changed across a gradient of predation potential and varied with exposure time.

Effects of drift- and benthic-foraging fish on the drift dispersal of three species of mayfly nymphs in a Japanese stream

Differences in the effects of two common predatory fishes, rainbow trout (Oncorhynchus mykiss) and freshwater sculpin (Cottus nozawae), on drift dispersal of the nymphs of three mayfly species, Baetis thermicus, Cinygmula sp., and Paraleptophlebia chocorata, were examined by manipulative field experiments using stream enclosures in a northern Japanese stream. The diel periodicity of prey consumption rate differed considerably between the two fishes; the prey consumption of the drift-foraging trout was greater at both dawn and dusk, whereas the benthic-foraging sculpin showed a higher consumption rate at night. The drift propensity at night was much greater than during the day for all the mayfly species in each of the trout, sculpin and fishless treatments, as well as under natural conditions with both fishes present. The nighttime drift propensities of the epibenthic grazers, B. thermicus and Cinygmula sp., were greater in the sculpin treatment than in trout and fishless treatments, and they did not differ between the trout and fishless treatments. By contrast, the nighttime drift propensity of P. chocorata, an infaunal collector-gatherer, did not differ among the treatments. The daytime drift propensity did not differ among the treatments for any of the mayfly species. Thus differences in drift response to the predatory fishes could be related to the characteristic microhabitats of the mayfly species. Moreover, the experiments demonstrated that benthic-foraging sculpin had greater overall effects on prey drift than drift-foraging trout.

Classification of northern Finnish lakes and the suitability for the stocking for brown trout ( Salmo trutta (L.) m. lacustris)

Because there are some 15 000 Finnish lakes exceeding 10 ha in area, there is a pressing need in Finland for the development of effective stocking strategies for various types of Finnish lakes. The most common predatory fish employed in stocking in Finland for the past few decades has been brown trout ( Salmo trutta (L.) m. lacustris), and the brown trout yield in lakes relies almost solely on stocking. Since the recourses of the fisheries managers are limited, it would be useful if an empirically derived lake classification scheme were made available for them, to enable them to plan and implement monitoring programmes to suit each individual lake. A cluster analysis (Ward's minimum-variance method) was used to classify 33 lakes in northern Finland on the basis of the yields of seven most common species: brown trout, vendace, whitefish, perch, pike, burbot and roach. The success achieved in the stocking of brown trout was compared between the various lake clusters. A discriminant analysis was used to develop a discriminant criterion to classify each lake into one of the clusters on the basis of species composition and ten environmental variables. The results suggested that, when based on catch statistics, cluster analysis can produce an objective classification scheme. Relative brown trout yield (kilograms per thousand fish released) seemed to be higher in the cluster with a higher proportion of vendace. The importance of the use of proper stocking rate for different kind of lakes was also revealed. Discriminant criterion based on both species composition and environmental variables rather reliably classified the lakes to correct clusters (76% and 70%, respectively). A scheme employing lake clusters could, thus, be used as a basis for management decisions on suitable stocking rate and which of the lakes are to be included into the stocking programmes of brown trout. The study produced some useful guide-lines to management programmes reducing the need to study all individual lakes in detail.

The trophic ecology of caridean shrimps in an eelgrass community

Four species of caridean decapods together represent a productive elements of the epifauna of eelgrass beds in Western Port, Australia. The guild is dominated by a palaemonid species, Macrobrachium intermedium Stimpson, which was found to have a mean annual density of approximately 50 individuals m −2 and an annual productivity of 3.4 g ash-free dry mass m −2. Analyses of shrimp diets indicated that three species, M. intermedium, Hippolyte caradina Holthuis and Chlorotocella leptorhyncus (Stimpson), are consumers of both animal and plant material, while a single (crangonid) species, Pontophilus intermedius (Fulton and Grant), is a specialized carnivore. Predation by shrimps may be responsible for the removal of substantial proportions of the productivity of cohabiting smaller invertebrates such as gastropod molluscs, peracaridean crustaceans and polychaetes, and probably eclipses the level of predation by fish. Plant detritus (along with associated microorganisms) is more prominent in shrimp diets during winter, and may be correlated with a reduced availability of animal prey during this period. Shrimps are consumed by a number of the common predatory fish and birds associated with eelgrass flats. Predation is concentrated on the two numerically dominant carideans and may be an important factor modifying the population structure of these species. It is concluded that the Caridea occupy a key position in trophic processes within the eelgrass system by (i) exerting a strong influence on the structure and dynamics of the lower trophic levels of the system; and (ii) by transferring a major proportion of their relatively high productivity to higher consumers.