Effectiveness of fishing gears to assess fish assemblage size structure in small lake ecosystems

摘要

Measurement of fish body-size distributions is increasingly used as a management tool to assess fishery status. However, the effects of gear selection on observed fish size structure has not received sufficient attention. Four different gear types (experimental gill nets, fine mesh bag seine, and two different sized mesh trap nets), which are commonly employed in the study area for fisheries surveys, were used to fish in five small (<200ha) lakes to evaluate differential catch in terms of species composition and assemblage size distributions. Kolmogorov-Smirnov tests revealed that, out of the five lakes and six comparisons, the four gear types captured fish of statistically similar size distributions in only one instance. Non-metric multi-dimensional scaling followed by a multi-response permutation procedure revealed that the species composition of fish captured by these gears also differs. These results support the notion that multiple gear types should be used to assess body-size distributions as well as fish assemblage composition.