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Lake Surface Area (lake + surface_area)

Distribution by Scientific Domains

Earth and Environmental Science	75%

Selected Abstracts

Contribution of native and non-native species to fish communities in French reservoirs

FISHERIES MANAGEMENT & ECOLOGY, Issue 3-4 2004
P. Irz
Abstract Previous studies showed that only 20% of the variability in fish community structure in French reservoirs could be explained by site characteristics. In addition, no relationship was found between the relative abundance of species and stocking effort. Therefore, deliberate or uncontrolled introductions are likely to be the source of a great part of the observed communities. The objective of this study was to assess the importance of species introductions in French reservoirs. Fifty-one reservoirs were sampled to obtain species presence/absence data. Local native (LNaR) and non-native (LNNR) species richness were negatively correlated. LNaR was strongly correlated to the lake surface area, depth and catchment area, whereas LNNR was independent of environmental variables. Furthermore, LNaR was positively correlated to regional native richness. Conversely, local total richness was independent of regional total richness, but was related to the reservoirs' environmental characteristics. It was hypothesised that the native fish communities in French reservoirs are unsaturated and species introductions lead to saturated communities. [source]

The development of the Finnish inland fisheries system

FISHERIES MANAGEMENT & ECOLOGY, Issue 4-5 2001
M. Sipponen
The efficiency of Finnish inland fisheries administration has improved during the past 15 years because of changes in fisheries legislation. The establishment of regional management units particularly has improved the practice of co-management, which has allowed the participation of many relevant interest groups in the decision-making process. The long-term private market equilibrium supply for recreational fishing with active types of gear accounted for 50% of the Finnish lake surface area. Presently the public sector has become involved in the supply of recreational fishing licences. The improvement in the system owes much to political initiatives. As regards commercial fishing, state-ownership of fishing grounds is a channel for recruitment into the occupation. Private ownership has led to a suboptimal allocation of fisheries resources, particularly in the commercial branch of the industry. However, by giving priority to social instead of economic goals the statutory fishery associations will help to maintain social and community values, which are locally important. [source]

Factors related to gizzard shad and the threadfin shad occurrence and abundance in Florida lakes

JOURNAL OF FISH BIOLOGY, Issue 2 2000
M. S. Allen
Gizzard shad Dorosoma cepedianum were collected in 23 and threadfin shad D. petenense were collected in 22 of the 60 Florida lakes sampled. Logistic regression equations were 94% effective for predicting gizzard shad occurrence from chlorophyll and lake surface area, and 84% effective for predicting threadfin shad occurrence from lake surface area and lake volume inhabited (PVI). Occurrence of both shad species was related positively to lake size. In lakes where gizzard shad or threadfin shad were collected, shad density and biomass of both shad species were related positively to chlorophyll. Gizzard shad populations were generally vulnerable to predation in lakes, with the per cent of gizzard shad ,200mm LT values exceeding 60% with few exceptions. Effects of gizzard shad and threadfin shad on fish community dynamics may be confined to relatively large (>100 ha) and fertile (chlorophyll >20,30,g l,1) Florida lakes. [source]

Inbreeding, outbreeding and environmental effects on genetic diversity in 46 walleye (Sander vitreus) populations

MOLECULAR ECOLOGY, Issue 2 2006
CHRISTOPHER J. CENA
Abstract Genetic diversity is recognized as an important population attribute for both conservation and evolutionary purposes; however, the functional relationships between the environment, genetic diversity, and fitness-related traits are poorly understood. We examined relationships between selected lake parameters and population genetic diversity measures in 46 walleye (Sander vitreus) populations across the province of Ontario, Canada, and then tested for relationships between six life history traits (in three categories: growth, reproductive investment, and mortality) that are closely related to fitness, and genetic diversity measures (heterozygosity, d2, and Wright's inbreeding coefficient). Positive relationships were observed between lake surface area, growing degree days, number of species, and hatchery supplementation versus genetic diversity. Walleye early growth rate was the only life history trait significantly correlated with population heterozygosity in both males and females. The relationship between FIS and male early growth rate was negative and significant (P < 0.01) and marginally nonsignificant for females (P = 0.06), consistent with inbreeding depression effects. Only one significant relationship was observed for d2: female early growth rate (P < 0.05). Stepwise regression models showed that surface area and heterozygosity had a significant effect on female early growth rate, while hatchery supplementation, surface area and heterozygosity had a significant effect on male early growth rate. The strong relationship between lake parameters, such as surface area, and hatchery supplementation, versus genetic diversity suggests inbreeding and outbreeding in some of the populations; however, the weak relationships between genetic diversity and life history traits indicate that inbreeding and outbreeding depression are not yet seriously impacting Ontario walleye populations. [source]