Fishing down, fishing through and fishing up: fundamental process versus technical details
By Konstantinos Stergiou and Athanassios Tsikliras
Marine Ecology Progress Series (2011) 441:295-301
“Fishing through, fishing up […] and the question of agreement between MTL from catches and surveys have been used to question fishing down the marine food web as well as the use of the marine trophic index as an effective ecosystem indicator…………
”We believe that fishing down, fishing through and fishing up the food web are not incompatible but only appear so because of confusion. Fishing down is an ecological process, which can be expected to either occur or not, i.e. it is a hypothesis which can be falsified and replaced by an alternative hypothesis that must also rely on ecological principles (rather than technicalities). In contrast, fishing through and fishing up reflect technical issues related to biases in the available data and/or to fishing behaviour and thus do not falsify fishing down………..
“Thus, MTL remains one of the most operational indices available for testing fishing down. It is without doubt that, in various cases, MTL will not be effective because of various technical confounding factors, which can be clarified by local experts. Undoubtedly, MTL can be misused, usually when confounding effects cannot be properly disentangled, and thus it must be used and interpreted with caution.”
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