Maximum length as an Indicator for Estimating Fisheries Exploitation

2012
02.02

In order to know whether the fishery has selective or non-selective fishing pattern, the impacts of fisheries to the fish community need to be clarified. The impacts of fisheries can be explained by the species resilience and susceptibility.

 

The susceptibility of species to gears can describe how the fish stocks react to fishing (Stevens et al., 2000; Jul-Larsen et al., 2002a). To define susceptibility and vulnerability of fish community to fishing gears, the analysis of life history characteristics are developed (Stobutzki et al., 2001; O’Malley, 2010).

 

Maximum length as one of kind life history characteristic was considered to be analyzed since it was able to represent the changes and variability of fish community as a response to fishing pressure (Welcomme, 1999; Stobutzki et al., 2001; King and McFarlane, 2003; Patrick et al., 2009). This will be ordered to know whether the stock variability and total fisheries in a certain area will generate such a form of fisheries selectivity (selective or non-selective).

 

According to Patrick et al. (2009) and Stobutzki et al (2001), maximum length (L-max) is used as an indicator of species’ relative recovery rate. It is correlated with productivity where the large fish tend to have the lower levels of productivity, since they live longer and their populations recover more slowly. The L-max analysis defined the condition of species group in fish community subject to their theoretical maximum length. Through this analysis the responses of the fish community in a certain area to fishing pressure will be revealed by performing the average length and catch rate analysis over decades and over mesh sizes category.

 

References:

[1] Jul-Larsen, E., Kolding, J., Overå, R., Nielsen, J. R. and Zwieten, P. A. M. v, Management, co-management or no-management? Major dilemmas in southern African freshwater fisheries. Synthesis report. In FAO Fish. Tech.Pap. 426/1. Rome: FAO., 2002a.

[2] King, J. R. and McFarlane, G. A., Marine fish life history strategies: applications to fishery management. Fisheries Management & Ecology 10, 249-264, 2003.

[3] O’Malley, S. L, Predicting Vulnerability of Fishes. In Department of Ecology and Evolutionary Biology, Vol. Master of science. Toronto: University of Toronto, 2010.

[4] Patrick, W. S., Spencer, P., Ormseth, O., Cope, J., Field, J., Kobayashi, D., Gedamke, T., Cortés, E., Bigelow, K., Overholtz, W., Link, J. and Lawson, P., Use of Productivity and Susceptibility Indices to Determine Stock Vulnerability, with Example Applications to Six U.S. Fisheries. (Ed, Service, U. S. D. o. C. N. O. a. A. A. N. M. F.). Seattle: Alaska Fisheries Science Center, 2009.

[5] Stevens, J. D., Bonfil, R., Dulvy, N. K. and Walker, P. A.,  The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems. ICES Journal of Marine Science: Journal du Conseil 57, 476-494, 2000.

[6] Stobutzki, I., Miller, M. and Brewer, D., Sustainability of fishery bycatch: a process for assessing highly diverse and numerous bycatch. Environmental Conservation 28, 167-181, 2001.

[7] Welcomme, R. L., A review of a model for qualitative evaluation of exploitation levels in multi-species fisheries. Fisheries Management and Ecology 6, 1-19, 1999.

 

 

 

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