The researchers propose that it is this assumption that has led to the collapse of lower trophic level species [34]. An overexploitation of these lower-trophic level species would be devastating to an ecosystem. In his trophodynamic ecosystem model, Gascuel concluded that fisheries targeting lower trophic levels have greater total yields. Gascuel notes that, “high exploitation rates associated selleck products to low trophic levels… can lead to collapse of total biomass, with

for instance a five times reduction in our simulations” [27]. This complete ecosystem collapse is likely due to the loss of prey for higher-level organisms as well as deleterious harvesting methodologies typically employed in low-level fisheries (e.g., bottom trawling which inherently requires benthic habitat degradation) [35]. Together, this evidence suggests that targeting of lower-level species for exploitation will cause detrimental effects throughout the food web because fishers are both decreasing abundance of the targeted species as well as directly competing with upper-level species. The increase to overfishing scenario would

encompass an increase in fishing effort across all trophic levels. In their 2010 Cyclopamine cost article, Branch et al. propose that this scenario of overfishing would account for the greatest percentage of collapsed stocks [5]. This seems likely, as the sensitive higher trophic level species, as discussed previously, would risk collapse under relatively light fishing pressure. This scenario, however, suggests that fishing pressure would continuously increase until the fishery capacity is reached. The constant increase in fishing pressure would certainly result in the population collapse of high-level piscivorous fish. In addition to the collapse of high-level species, an increase in fishing pressure is also experienced at lower trophic

levels. This Fludarabine in vivo infinite increase in fishing pressure will inevitably lead to the collapse of all stocks. The sequential increase in fishing pressure on specific trophic levels, however, would likely result in the sequential collapse of fisheries, giving managers an opportunity to prevent additional collapses. A steady increase in fishing pressure across all trophic levels, however, could result in a simultaneous decline and eventual collapse of all stocks in an ecosystem, providing managers with no opportunity to react. In Trevor Branch’s 2010 analysis, he concluded that fishing down and fishing through would both result in a declining catch-based MTL. Fishing down would yield a steeper decline initially, however the two scenarios would reach the same minimum trophic value ( Table 1). In contrast, the number of collapsed species would be much higher in the fishing down scenario, likely due to abundant trophic cascades. Branch also concluded that the increase to overfishing scenario would result in a minimal change in MTL, but the highest percentage of collapsed species [5].