Perch Caught Research Articles

Trends in Abundance and Mean Size of Fish Captured in Gill Nets from Minnesota Lakes, 1983–1997

AbstractWe investigated seasonal and 15‐year trends in catch per unit effort (CPUE) and mean weight of black crappies Pomoxis nigromaculatus, ciscoes Coregonus artedi, northern pike Esox lucius, walleyes Sander vitreus (formerly Stizostedion vitreum), white suckers Catostomus commersoni, and yellow perch Perca flavescens captured in gill nets from 433 Minnesota lakes between 1983 and 1997. Seasonal trends were modeled using least‐squares linear and polynomial regressions, and interannual trends were investigated with a linear mixed‐effects model and an augmented serially alternating design. Four of the six species exhibited significant seasonal trends. Walleye CPUE increased linearly, whereas walleye and cisco mean weight and northern pike CPUE decreased linearly from spring through fall. Cisco CPUE and yellow perch mean weight exhibited curvilinear relationships, decreasing from spring through summer and then increasing from summer through fall. Two species exhibited significant 15‐year trends across Minnesota from 1983 to 1997: Walleyes experienced significant positive trends in both CPUE and mean weight, probably benefiting from more efficient stocking or warmer June temperatures, and black crappies experienced a significant decreasing trend in CPUE, possibly due to replacement by walleyes, loss of spawning habitat, or increased harvest by recreational anglers. Catches of ciscoes, northern pike, white suckers, and yellow perch in gill nets were unchanged across Minnesota between 1983 and 1997, indicating population stability. The results of this study suggest that lakes should be sampled with gill nets at the same time of year or that catches should be corrected to a common date to allow direct comparisons among lakes. The monitoring of trends in fish populations and habitat variables using standardized sampling on broad spatial scales should be more widely used to detect changes, generate hypotheses regarding these changes, and focus research and management efforts.

Altered steroid metabolism in several teleost species exposed to endocrine disrupting substances in refuse dump leachate

Endocrine disruption associated with reproductive failure has been reported previously in female perch ( Perca fluviatilis) and roach ( Rutilus rutilus) from Lake Molnbyggen in Sweden and in female brook trout ( Salvelinus fontinalis) from Vadbäcken, a stream emptying into Molnbyggen. Both Molnbyggen and Vadbäcken have been contaminated by toxic leachate from a municipal refuse dump. In this study, female perch were caught in Molnbyggen and the reference lake, Lake Djursjön, to further investigate the endocrine mechanism behind the significant numbers of sexually immature (SIM) female perch in Molnbyggen. Blood plasma analysis of progesterone (P), 17α-hydroxyprogesterone (17α-OHP), testosterone (T), and 17β-oestradiol (E2), as well as analysis of brain aromatase activity (P450arom), were carried out. The exceptional high numbers of SIM female perch in Molnbyggen was confirmed in February 1999. In July 1999, at an early stage of oogenesis, perch from Molnbyggen showed significantly decreased gonadosomatic index (GSI) and aromatase activity. The presence of aromatase inhibiting substances in lake sediments were therefore tested in vitro. The aromatase activity was dose-dependently inhibited by clotrimazole, reaching 50% inhibition at a concentration of 0.9 μM. Aromatase inhibiting substances were found both in Molnbyggen and reference sediment extracts, indicating that they were naturally occurring substances and not of anthrophogenic origin. The similar decrease in levels of circulating steroids (P, 17α-OHP, T, and E2), aromatase, and GSI therefore suggest that the low aromatase activity is due to down-regulation rather than inhibition. To further investigate the steroidogenesis prior to T, P, and 17α-OHP were analysed in perch caught in 1997 and 1998 in Lakes Molnbyggen, Kvarntjärn (downstream), Yxen (upstream), and Djursjön, in female roach caught in Molnbyggen and Djursjön in 1997, and in brook trout caught in Vadbäcken and the reference stream Björntjärnsbäcken in 1998. The absence of differences in P and 17α-OHP levels, combined with a significantly lower T level in female perch and roach from Molnbyggen in 1997, could be the result of either increased metabolism and excretion of T, or a disruption downstream of 17α-OHP formation. The unaffected P levels and significantly lower 17α-OHP levels, together with significantly decreased T and E2 levels, found in adult (>45 g) female brook trout from Vadbäcken, further indicated that an altered steroidogenesis downstream of P is one possible mechanism underlying the low T levels and thus the high number of SIM female fish, since too low T levels might be insufficient to activate the brain–pituitary–gonadal axis.

Long-term development in a Baltic fish community exposed to bleached pulp mill effluent

Observations near a Swedish pulp mill at the Bothnian Sea during 1982-1992 revealed low fish abundance and a disturbed community structure. The presence of endocrine disrupting or toxic substances in effluent water was indicated by biomarker responses, impaired reproduction and stimulated growth in perch (Perca fluviatilis). In 1992 the bleaching process was altered and a secondary treatment system was installed, improving the quality and decreasing the amount of effluent. This paper presents the results of follow-up studies during 1995-1998 with the objective to analyse any recovery of the fish community due to changes in mill operations. Although abundance and diversity of the fish community did recover, an effect of enrichment, indicated by high catches of cyprinids, was still visible in the vicinity of the mill outlet. Sexual maturation was delayed, gonad development was retarded, average growth rate was faster, and the condition factor was higher in perch caught in the vicinity of the effluent outlet, than in perch captured elsewhere. It is concluded that substances inhibiting reproduction and causing growth disturbance were still present in the effluents in effective concentrations.

Effects of habitat and food resources on morphology and ontogenetic growth trajectories in perch.

Studies on resource polymorphism have mainly been considered at the end stage of ontogeny, whereas many species undergo diet changes as they grow. We conducted a field survey to analyze the role of adaptive variation during ontogeny in Eurasian perch (Perca fluviatilis). We caught perch from the littoral and pelagic zones of a lake to investigate whether perch differ in morphology and diet between these habitats. We also investigated whether there were any differences in morphological trajectories during the ontogeny of perch collected from the two habitats. We found that perch caught in the littoral habitat, independently of size, had a deeper body, larger head and mouth and longer fins than perch caught in the pelagic zone. Macroinvertebrates and fish dominated the diet of littoral perch, whereas the diet of the pelagic perch consisted mainly of zooplankton and to some extent fish. Independently of size, the more streamlined individuals had a larger proportion of zooplankton and a smaller proportion of macroinvertebrates in their diet than the deeper-bodied individuals, indicating a relation between diet and morphology. Some morphological characters followed different ontogenetic trajectories in the two habitats; e.g. the changes to a deeper body and a larger head were faster in the littoral than in the pelagic perch. The relationship between the length of perch and the size of the mouth and fins also differed between perch from the two habitats, where the increase in the length of the pelvic fin and the area of the mouth increased faster with size in the littoral perch. Our findings show that variation in morphology between habitats differs during ontogeny in a way that corresponds to functional expectations for fish species that occupy these habitats.

Changes in Bluegill, Black Crappie, and Yellow Perch Populations in Wisconsin during 1967–1991

Abstract A common perception among fisheries managers is that the mean size and number of fish within populations has decreased over time. We examined changes in size of bluegills Lepomis macrochirus, black crappies Pomoxis nigromaculatus and yellow perch Perca flavescens in fyke net samples during 1967–1991 to determine changes in size of fish and in creel surveys during 1980–1991 to determine changes in size of fish harvested and total angler catch and harvest. Mean size and proportion of large bluegills and yellow perch in fyke net samples decreased throughout the sample period. Total catch and harvest of bluegills, black crappies, and yellow perch decreased significantly during 1980–1991. Although mean size of bluegills and yellow perch harvested did not change during 1980–1991, the proportion of large bluegills harvested decreased and the proportion of large black crappies harvested increased. We conclude there was a small, but significant reduction in the size of bluegills and yellow perch in the po...

Relationship between Larval and Juvenile Yellow Perch Abundance in Eastern South Dakota Glacial Lakes

Abstract We sought to determine if abundance of larval yellow perch Perca flavescens could predict abundance of age-0 juvenile perch in late summer. Yellow perch larvae and juveniles were sampled from six eastern South Dakota glacial lakes in 1997. The number of age-0 yellow perch caught per seine haul in late summer was positively related to larval abundance in late May and early June (N = 6, r = 0.90, P = 0.01). When data collected from two eastern South Dakota lakes in 1995 and 1996 were added to this assessment, we also found a significant positive relation (N = 10, r = 0.88, P = 0.0009). Thus, biologists in eastern South Dakota can use larval yellow perch abundance as an early indicator to determine which water bodies are likely to have a weak naturally produced year-class and then can evaluate the success of fingerling perch stocking strategies.

Abnormalities of a gill cover bone, the operculum, in perch Perca fluviatilis from a pulp mill effluent area

Abnormalities of a gill cover bone, the operculum, were found in perch Perca fluviatilis from an area affected by pulp mill effluents in the Gulf of Bothnia, Baltic Sea, Sweden. One of the abnormalities was expressed as a shortening of the distal part of the operculum, and was termed opercular deformity. This deformity was quantified by taking two measurements of the operculum. The second abnormality was manifested as craterous formations on the operculum. Both abnormalities were studied using a sample of opercula collected in the pulp mill effluent area between the years 1982 and 1989. The maximum prevalences of the abnormalities, 34% for the craterous formation and 20% for the opercular deformity, were found in 1983 and 1984, respectively. In a reference area the prevalences were 1% and 1.4%, respectively. After 1984, the prevalences decreased together with prevalences of other fish diseases and deformities in the same area. This coincided with a reduction in concentrations of effluent. The observed high prevalence of the opercular deformity and the craterous formations were attributed to the effects of the pulp mill effluent. In addition, an analysis of the biochemical composition opercula from perch caught in another pulp mill effluent area showed a dose-dependent alteration of several constituents, indicating a relationship with exposure to the effluent. This study shows the potential of opercular abnormalities to monitor effects of pulp mill effluents, and also, it is suggested, for retrospective studies on large samples of opercula used for age determination in ecological studies of fish.

Lake Victoria fisheries: the Kenyan reality and environmental implications

The introduction of the Nile perch into Lake Victoria has dramatically altered the fishery in that lake and contributed to the decline of the fishery for indigenous tilapias. One sector of the fishery in Lake Victoria has benefitted from the Nile perch introduction, although catches have declined in recent years. Inefficient enforcement of fisheries regulations has had a detrimental effect on indigenous species but may also have contributed to the recent decline in Nile perch catches. Fisheries development plans have tended to favour capital-intensive fisheries and to ignore small scale subsistence fisheries. A case study at Wichlum Beach on the Kenyan shores of Lake Victoria has revealed the efficiency of traditional fishing and fish drying methods as well as the high ecological costs of the practice of kiln-drying Nile perch. Forty-five tons of firewood are used per month at Wichlum Beach alone for kiln-drying perch. The increased economic viability of the fishery has attracted professionals into the industry and resulted in the development of an export-oriented trade. The Yala Swamp adjacent to Lake Victoria has been extensively drained as part of a large land reclamation scheme and more draining is planned. Increased environmental awareness in Kenya, and Kenya's membership in the Convention on Wetlands of International Importance, has resulted in a critical review of these plans.

An analysis of the distribution of fish species in a large prairie lake

The distribution of fishes in Dauphin Lake, a large, shallow, turbid, prairie lake in west‐central Manitoba, was examined using gillnets. Catch per unit effort was used to assess differences in distribution thai may be attributed lo year, season, lake zone (inshore, offshore), substratum, water depth, water temperature, turbidity and presence of other fish species. Although 13 species were caught, only the distributions of the six most abundant was analysed. Variation in number of species caught was attributed mainly to lake zone, water depth and water temperature. White sucker (Catastomus commersoni) distribution can be explained by zone and temperature. Shorthead redhorse (Moxostoma macrolepidotum) catches were related to depth and temperature. Cisco (Coregonus artedii) catches varied with year, zone and temperature. Variances in northern pike (Esox Indus) distribution reflected year and zone. Walleye (Stizostedkm vitreum) varied with year, depth and temperature and differences in the catches of yellow perch (Pertaflurescens) were attributed to year, depth, temperature and turbidity. They were also positively correlated to the numbers of northern pike caught.

An analysis of the distribution of fish species in a large prairie lake

The distribution of fishes in Dauphin Lake, a large, shallow, turbid, prairie lake in west-central Manitoba, was examined using gillnets. Catch per unit effort was used to assess differences in distribution thai may be attributed lo year, season, lake zone (inshore, offshore), substratum, water depth, water temperature, turbidity and presence of other fish species. Although 13 species were caught, only the distributions of the six most abundant was analysed. Variation in number of species caught was attributed mainly to lake zone, water depth and water temperature. White sucker (Catastomus commersoni) distribution can be explained by zone and temperature. Shorthead redhorse (Moxostoma macrolepidotum) catches were related to depth and temperature. Cisco (Coregonus artedii) catches varied with year, zone and temperature. Variances in northern pike (Esox Indus) distribution reflected year and zone. Walleye (Stizostedkm vitreum) varied with year, depth and temperature and differences in the catches of yellow perch (Pertaflurescens) were attributed to year, depth, temperature and turbidity. They were also positively correlated to the numbers of northern pike caught.

Modelling fluctuations and optimal harvesting in perch populations

Tyutyunov, Yu., Arditi, R., Bfittiker, B., Dombrovsky, Yu. and Staub, E., 1993. Modelling fluctuations and optimal harvesting in perch populations. Ecol. Modelling, 69: 19-42. A mathematical model of perch (Perca fluviatilis L.) was elaborated, based on the data for ten Swiss lakes. The aim is management of a commercially exploited population. This required elucidation of dynamics of perch stocks and catches. Statistical data analysis demonstrated complicated population dynamics, including cycles of different periods and chaos. The model describes age and sex structure, nonlinear reproduction (including the effects of cannibalism and competition), individual growth, and harvesting, which depends on fishing effort and mesh size of nets. Bifurcation analysis of the model showed the presence of chaotic dynamics and, hence, high sensitivity to initial conditions. Sensitivity to model parameters was also investigated. Simulation analysis of the fishing process was done on the basis of data from Lake Constance. A multiobjective problem of harvest maximization combined with variance minimization was investigated. The isopleths of the annual harvest and of its dispersion were calculated. Pareto-effective strategies, accounting for trade-off between average harvest and its stability were evaluated. A recommendation was given for optimal mesh size and fishing effort. User-friendly software was developed for IBM PC compatible computers, which can be used to investigate a broad class of age-structured populations.

Evidence of predatory control of yellow perch (Perca flavescens) recruitment in Lake Erie, U.S.A.

Predation can be a major factor in recruitment success of yellow perch (Perca flavescens Mitchitl). Trawl catches of age‐0 yellow perch in western Lake Erie declined from 870·3 per trawling h in June to 3·3 per trawling h in late July 1988. Coincident with the decline in relative abundance of age‐0 yellow perch we found large numbers of age‐0 yellow perch in the stomachs of small walleyes (Stizostedion vitreum Mitchill). From this evidence we hypothesized that predation by walleyes may have caused the demise of the 1988 year‐class of yellow perch. We used a population and bioenergetics modelling approach to estimate the impact of walleye predation on the abundance of age‐0 yellow perch. Modelling showed that 6·8 × 109 age‐0 yellow perch that had attained 18 mm total length (t.l.), were eaten by small (age‐2 and younger) walleye from June through July 1988. We estimated that walleye ate 28·4–89·7% of the yellow perch reaching 18 mm t.l. during 1988. The majority of this predation (77% of total) was by the abundant age‐2 cohort of walleyes. We concluded that, even in a large system such as Lake Erie, predation can play a major role in structuring year‐class strength of yellow perch and, thus, management of percid fisheries should be conducted on a fish‐community basis.

Fyke-Net and Gill-Net Size Selectivities for Yellow Perch in Green Bay, Lake Michigan

Abstract We estimated a fyke-net selectivity function for yellow perch Perca flavescens in Green Bay, Lake Michigan, by comparing length-frequency distributions of yellow perch captured in fyke nets with different mesh sizes in 1986. Using a length—girth relationship for Green Bay yellow perch, we expressed selectivity as the ratio of girth (G) to effective mesh perimeter (P), which was 5–7% less than nominal mesh perimeter. Then, fitting an existing gill-net selectivity function to the Green Bay yellow perch fishery, we found fyke-net and gill-net selectivities were similar, with similar G /P ratios, but fyke nets had smaller effective mesh perimeters and thus were more efficient at capturing smaller yellow perch for any given mesh size, The derived fyke-net selectivity function can be used to determine mesh sizes that minimize the sublegal catch of yellow perch in this fishery and could be applied to entrapment gear in other yellow perch fisheries, given data on the length–girth relationships and effect...

Environmental Variability and the Stability in the Outcome of the Professional Fishery in Lake Ijssel, the Netherlands

Fishermen experience natural variability through variations in their annual catch per species. In Lake IJssel the catches of pikeperch, Stizostedion lucioperca, in 101 mm gillnets show the largest variability, compared with the variability in the catches of perch, Perca fluviatilis, in these nets and of eel, Anguilla anguilla, in fykenets. Variability in recruitment is the major cause of annual variation in the catch of pikeperch and perch. Year-class strength of pikeperch is highly correlated with summer temperature. Effort limitation provides a marginal gain in stabilising the annual catch in the Lake IJssel pikeperch and perch fishery. In spite of severe over-exploitation, the total outcome of the Lake IJssel fishery has been stable over the last decade, because of the low variability in the catches of eel and because all together four species are exploited.

Relationship between metallothionein, copper and zinc in perch ( Perca fluviatilis) environmentally exposed to heavy metals

Hepatic levels of Cu, Zn and metallothionein (MT) in perch, caught in a Cu/Zn gradient from a brassworks, reflected the water concentration of Cu (1·0–9·4 ppb) and Zn (0·56–59 ppb). Significant correlations were found between hepatic Cu and MT levels ( r = 0·72), and between Zn and MT levels ( r = 0·69). There was an increase of the amount of Cu and Zn in the cytosolic fraction of the liver with increased hepatic levels of the metals. When liver samples. from perch caught at the most contaminated location, were run on a gel filtration column (Sephadex G-75) 78% of the cytosolic Cu and 24% of the Zn in the cytosol eluted together with MT.

Biomonitoring of oil spill in a boreal archipelago by xenobiotic biotransformation in perch ( Perca fluviatilis)

The effect of the accidental oil spill (250 tons) in a boreal archipelago (Gulf of Bothnia, Vaasa, Finland) on xenobiotic metabolism of local perch ( Perca fluviatilis) was monitored for 1.5 years. The monooxygenase (benzo[ a]pyrene, 7-ethoxycoumarin O-deethylase, 7-ethoxyresorufin O-deethylase) and conjugation (UDPglucuronosyltransferase, glutathione S-transferase) activities of perch liver were determined from control areas and those areas where oil had spilled. Only a slight induction in monooxygenase activities was seen in perch caught near the oil spill 4 months after the accident. The induction of monooxygenase activities detected with the fuel oil in laboratory experiments was, however, clear. After a single dose, it rose rapidly and quickly disappeared. Conjugation enzyme activities were not affected in the laboratory.

Feeding energetics and angling catches of spangled perch, Leiopotherapon unicolor (Günther 1859), (Percoidei : Teraponidae)

Spangled perch, Leiopotherapon unicolor, in aquaria reduced their daily ration as water temperature decreased. Fish held at a mean temperature of 16.8�C did not grow significantly over a period of 180 days, whereas individuals maintained near 22.6�C showed a weight increase of 32.8% over the same period. Both groups of fish metabolized approximately 38% of their energy intake, excreted 57% and allocated 5% for growth. Fish adapted to the lower temperature regime consumed 10.81 kJ day-1 compared with a predicted value of 2.08 kJ day-1 for fish adapted to warmer temperatures and exposed to 16.8�C. Spangled perch appear to repartition energy resources at some point below 16�C to make up for a shortfall in energy intake caused by reduced ration. Fish in their natural environment may also reduce food intake at low temperatures, as spangled perch caught by angling in winter had less food in their stomachs (0.31% body weight) than fish caught in other seasons (4.87% in spring to 3.13% in autumn). Catch rate in winter (< 1 fish per angler hour) was also lower than that in other seasons (> 5 fish per angler hour).

Changes in the Multispecies, Winter Angling Fishery of Lake Simcoe, Ontario, 1961–83: Invasion by Rainbow Smelt,Osmerus mordax, and the Roles of Intra- and Interspecific Interactions

Winter creel surveys revealed major changes in the abundance of five fish species (lake trout, Salvelinus namaycush, lake whitefish, Coregonus clupeaformis, lake herring, Coregonus artedii, yellow perch, Perca flavescens, and rainbow smelt, Osmerus mordax) in Lake Simcoe (1961–83). Variations in abundance were in part caused by intra- and interspecific factors. Catches in alternate years for both lake herring and rainbow smelt were inversely correlated, suggesting negative interactions between their young-of-the-year and yearlings. Similarly an inverse relation between parental stock size and recruitment explained a significant component of the catch variation of lake herring and yellow perch. Natural recruitment of lake trout declined during the 1950s (associated with eutrophication effects), and in the early 1960s, rainbow smelt invaded the fake. Lake whitefish abundance declined in the early 1970s as smelt abundance increased; the decline in whitefish recruitment was probably caused by interaction between smelt and whitefish young-of-the-year. Catches of yellow perch were positively correlated with rainbow smelt and negatively correlated with lake whitefish. Lake herring also increased when lake whitefish density was low. Increased abundance of lake trout after 1975 (due to stocking) appears to have resulted in lower densities of lake herring, rainbow smelt, and yellow perch and the reestablishment of lake whitefish recruitment at a low level. These results suggest that a large predator (lake trout) can have a major influence on the structure of a fish community, by direct and indirect effects.

Short-term effects of liming on perch Perca fluviatilis populations in acidified lakes in South-West Sweden

Gill net catches of perch Perca fluviatilis in eight acidified lakes immediately before liming are compared] with catches in the same lakes two years after liming. Simultaneously, six control lakes, not limed, were investigated with the same procedures. A significant increase in the average catches of perch was found in the limed lakes, but not in the control lakes. This result confirms earlier reports, although seldom supported with data from controls, on successful recovery after liming.

Effets combinés de la pêche et de l'eutrophisation sur la perche (Perca fluviatilis L.) dans les eaux vaudoises du Léman

Catches of perch have strongly decreased in Lake of Geneva from 1975 to 1981. This decrease was attributed to the impact of overfishing, enhanced by the accelerated growth of perch. Therefore, too many perches were captured before their first reproduction and the stocks of reproducers were strongly reduced. Furthermore, adverse meteorological conditions occurred probably during several periods of reproduction. The accelerated growth of perch was attributed to the combined effects of increasing eutrophication (more food available) and of overfishing (decreased perch density in the shoals).