Potential effects of bycatch from the squat lobster fisheries in central Chile on the benthic ecosystem: a survey data approach

Abstract

In Chile, bottom trawling for squat lobsters is one of the most important crustacean fisheries. The fishery has been monitored for the past 15 years to assess the resource status, spatial distribution and effects on benthic species. Understanding the interactions of fishing and non-fishing activities with the benthic communities is of critical importance to estimate the potential bycatch of important economic species from fishing operations and to determine adequate spatial and temporal fishing bans. In this study we characterised the community of the main non-target species caught during historical squat lobster biomass surveys from 2000 to 2015 and interpreted the species included as potential bycatch of the fishery. Four ecological assemblages were found that differed in abundance but not in species richness, which suggests that the community structures did not differ among the areas, but rather in the relative abundances of the species. In addition, we created habitat suitability maps for the groups identified and discuss the effects of the environment and the survey method on the distribution of the groups. Managers can use this information to detect regions with high bycatch risk for demersal trawl fisheries and understand the potential interaction of fishing operations with the environment.

Spatio-temporal patterns of the crustacean demersal fishery discard from the south Humboldt Current System, based on scientific observer program (2014–2019)

“…The cumulative species curves were constructed utilizing the function ‘specaccum’ from the package ‘vegan’ for R [ 31 ], using the exact estimation method. To determine the co-occurrence of the main discarded species, species representing over 2% of the frequency of occurrence were used, thus avoiding rare species in the analysis [ 14 ]. For exploring the spatio-temporal variation in catch composition, CPUA was transformed with log(x+1) to reduce the relative importance of dominant species (e.g., Chilean hake), and non-metric multidimensional scaling (nMDS) was used for ordination analysis, using the metaMDS function of the ‘vegan’ package [ 31 ], based on the Bray-Curtis similarity index.…”

“…Two core issues are 1) the predominant ‘monospecific approach’ to fisheries, which has curtailed our capacity to visualize fished species within complex interactive communities to advance toward an ecosystem-level approach [ 12 ], and 2) our still primordial understanding about how these systems respond to natural and anthropogenic environmental variation [ 13 ]. Indeed, the lack of scientific information about exploited ecosystems and their spatial and temporal variability over scales relevant to fisheries management has hampered efforts to implement better management and adaptation strategies in the face of climate change [ 14 ].…”

“…For demersal fauna, it is well known that regional and basin-scale meteorological and oceanographic processes, as well as their interactions with topography, can have an impact on population [ 15 ] and community levels [ 16 ]. The demersal community of the HCS has been described using prospective surveys, which is dominated by the Chilean hake Merluccius gayi , bigeye flounder Hippoglossina macrops , and nylon shrimp Heterocarpus reedi [ 14 , 17 , 18 ]. Three to four groups of species assemblages have been previously identified for demersal fishes and crustaceans [ 14 , 17 , 19 ] based on the depth distribution of the species and trophic interactions.…”

“…The demersal community of the HCS has been described using prospective surveys, which is dominated by the Chilean hake Merluccius gayi , bigeye flounder Hippoglossina macrops , and nylon shrimp Heterocarpus reedi [ 14 , 17 , 18 ]. Three to four groups of species assemblages have been previously identified for demersal fishes and crustaceans [ 14 , 17 , 19 ] based on the depth distribution of the species and trophic interactions. However, intra-annual variability and its dependence on surface physical processes are poorly understood.…”

Percentage of the bycatch and discard composition in artisanal bottom trap fisheries

“…Globally, it is estimated that 40% of marine catches are bycatch (Rudershausen et al, 2016). The many bycatches are essential in fisheries because of their impact on marine ecosystems, so a management effort is needed (Wardhani, 2012;Montero et al, 2020) to suppress bycatch, one of which is by using selective fishing gear on the fishing catches. This opinion is corroborated by Hall et al (2000) that catching fish not targeted will affect species diversity and aquatic ecosystems because bycatch not consumed or disposed of if continuously exploited will affect the food web.…”