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

Abstract

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 (< 200 ha) 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.

Migration and population structure characteristics of the small yellow croaker Larimichthys polyactis in the southern Yellow Sea

“…The proportion of females of the sailfish (Istiophorus albicans) captured in the period of 1991-2007 was 0.575 from a longline fishery and 0.331 from a drift-gillnet fishery (Arocha et al, 2010). Many studies have reported differences in gear selection for fisheries resources, with an emphasis on assessing fish assemblage composition and body-size distributions (Cvetkovicet al, 2012;Clement et al, 2014). The influence of the fishing gear type on the sex ratio of commercial species has not received sufficient attention.…”

Relationships between habitat characteristics and round goby abundance in Lakes Michigan and Huron

“…Differences in fish assemblages between habitats, however, may in part be attributed to gear bias. The fyke nets that were used for sampling capture higher numbers of small-bodied species compared to boat electrofishing, gillnets, and large-mesh trap nets Clement et al, 2014). Any differences in fish assemblages based on body size or mobility between wetland and open water habitats may not be well-detected using small fyke nets.…”

Fish community size structure of small lakes: the role of lake size, biodiversity and disturbance

“…The island is approximately 21 km long and 10 km wide with an area of 144.45 km 2 . There are seven inland lakes on the island, of which six were sampled (Egg, Barney, Greene's, Fox, Font, and Geneserath; in habitat, especially in broad terms such as lake area, mean and maximum depth, vegetative cover, and substrate types (Clement et al 2014). Similarly, the water chemistry of the lakes differs (described by Harris et al 2011); however, it is unlikely that water chemistry has affected the distributions of the largely tolerant species inhabiting these lakes.…”

“…The smaller of the two nets, 0.5 m tall frames, were fished in habitats <0.5 m deep, while the taller nets, with 1 m tall frames were fished in habitats >0.5 m but <1.5 m deep. The deep water trap net was used in habitats >1.5 m but <4 m deep and had 25.4 mm mesh and a 22.86 m long lead (Clement et al 2014). These gears were chosen because they could sample all habitats and were found to capture the most species and most size classes in the sampled lakes without overlap of size classes (Clement et al 2014).…”

“…The deep water trap net was used in habitats >1.5 m but <4 m deep and had 25.4 mm mesh and a 22.86 m long lead (Clement et al 2014). These gears were chosen because they could sample all habitats and were found to capture the most species and most size classes in the sampled lakes without overlap of size classes (Clement et al 2014). Identification and enumeration were made to the specieslevel and the TLs (mm) of all fish were measured except for small (<100 mm), highly abundant species which were sub-sampled.…”