Fishing, rather than temperature, has the most prominent effect on size structure of exploited fish populations
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Chen-Yi Tu and Chih-hao Hsieh
Institute of Oceanography, National Taiwan University
A study by graduate students Chen-Yi Tu, Kuang-Ting Chen and Professor Chih-hao Hsieh, found that fishing has the most prominent effect on the temporal variation of size structure of exploited populations through a global-scale meta-analysis. This work is published in Scientific Reports (2018, May).
Size structure of a fish stock plays a crucial rule in sustaining the population. Although previous studies found evidences of fishing and temperature effects on size structure of exploited populations, their relative contributions and interaction remain relatively unexplored. Also, it remains unclear whether univariate size-based indicators (SBIs) such as mean length could represent the entire size structure and the status of a population.
To address these issues, the team employed the variation partitioning approach to examine the variation of size composition in response to fishing and warming. The team analyzed 28 fish stocks from 3 major fishing areas (West coast of US, Alaska, North Sea). This analysis finds fishing as the prominent effect on size structure variation in the exploited populations. Moreover, fishing can elevate the sensitivity of exploited populations to temperature. This study indicates that variation partitioning can provide complementary information to univariate SBIs. The findings have implications for fisheries management in light of climate changes.
Figure 1. Temporal variation of size composition of exploited fish stock (a) in response to fishing mortality and temperature were analyzed through variation partitioning (b). This analysis attributes the variation of size composition into fractions explained by fishing, temperature and the interaction. Fishing explains most of the variation, particularly in demersal and bathydemersal fishes (c). In addition, the fish stocks experienced higher variability in fishing is more responsive to the temperature effect in their size structure (d), suggesting that fishing may elevate the sensitivity of exploited stocks to environmental effects.
Reference:
Tu, C. Y., K. T. Chen, and C. H. Hsieh (2018) Fishing and temperature effects on the size structure of exploited fish stocks. Scientific Reports. 8:7132.