Prospects for Fishery‐Induced Collapse of Invasive Asian Carp in the Illinois River

Abstract

Prospectos de un colapso inducido por pesca en la carpa asiática del Río Illinois RESUMEN: . La carpa asiática amenaza con invadir el Lago Michigan a través del sistema de vías acuáticas del área de Chicago, lo cual podría acarrear serias consecuencias en las tramas tróficas de los grandes lagos. Además de los esfuerzos llevados a cabo para impedir el ingreso de estos peces al Lago Michigan mediante barreras eléctricas, el estado de Illinois ha iniciado un programa de pesca en el Río Illinois, cuya finalidad es reducir la densidad poblacional a través de una pesca comercial intensiva. En este estudio se exploran los prospectos de un colapso de la carpa asiática por medio de un régimen de pesca intensiva. Sobre la base de un meta-análisis de datos demográfi-cos, se desarrolla un modelo de simulación dinámica para comparar el desempeño de estrategias de explotación tanto reales como alternativas para el Río Illinois. Las proyecciones del modelo sugieren que, de mantenerse las tasas de captura por debajo de 0.7 o si la pesca continua siendo selectiva a tallas (dirigiéndose a peces >500 mm o <500 mm) o a especies (carpa cabezona), entonces es poco probable colapsar la carpa asiática en el Río Illinois, aunque la biomasa se puede reducir considerablemente. Se argumenta que, pese a lo anterior, es posible lograr el nivel de esfuerzo pesquero predicho por el modelo, necesario para colapsar las poblaciones de la carpa asiática, si la pesca comercial se expande y se combina con incentivos económicos con tal de mejorar la selectividad a la talla y a las especies objetivo. ABSTRACT: Invasive Asian Carp are threatening to enter Lake Michigan through the Chicago Area Waterway System, with potentially serious consequences for Great Lakes food webs. Alongside efforts to keep these fishes from entering LakeMichigan with electric barriers, the state of Illinois initiated a fishing program aimed at reducing their densities through intensive commercial exploitation on the Illinois River. In this study, we explore prospects for the "collapse" of Asian Carp in the Illinois River through intensive fishing. Based on a meta-analysis of demographic data, we developed a dynamic simulation model to compare the performance of existing and alternative removal strategies for the Illinois River. Our model projections suggest that Asian Carp in the Illinois River are unlikely to collapse if existing harvest rates are kept below 0.7 or fishing continues to be size selective (targeting only fish >500 mm or <500 mm) or species selective (targeting mostly Bighead Carp), although their biomasses could be greatly reduced. We argue that it would still be possible to achieve fishing effort targets predicted by our model to collapse the Asian Carp populations if efforts to expand commercial fishing are combined with economic incentives to improve size selectivity and species targeting.

Recruitment sources of invasive Bighead carp (Hypopthalmichthys nobilis) and Silver carp (H. molitrix) inhabiting the Illinois River

“…If enhanced commercial harvest is restricted to the Illinois River, it appears likely that immigrants would replenish Silver Carp stocks in the Illinois River without additional efforts to limit fish movement such as installation of barriers at dams (Conover et al 2007) given the substantial contribution of recruits from the middle Mississippi River to all three reaches of the Illinois River. Our findings regarding recruitment sources of Bighead and Silver carps in the Illinois River will be important for refining recently developed simulation models for predicting population responses to harvest and development of spatially-explicit strategies to achieve fishery-induced collapse (Tsehaye et al 2013). We also anticipate that otolith microchemistry and stable isotope analyses may be applicable to other portions of the expanding, non-native ranges of Bighead and Silver carps to identify their principle recruitment sources and inform development of control strategies to limit their range expansion and impacts.…”

“…Age-0 bigheaded carps have also been collected from connected floodplain lakes along the Illinois River (Pegg et al 2002;DeGrandchamp et al 2007); however, the relative importance of these floodplain lakes and low-velocity river channel margin habitats as nursery areas for Bighead and Silver carps is also unknown. A recently developed simulation model indicated that harvesting all sizes of Bighead and Silver carps is required to achieve fishery-induced collapse (Tsehaye et al 2013). Thus, improved understanding of natal environments and early life habitat use of Bighead and Silver carps is particularly important to determine the appropriate spatial scale for enhanced commercial harvest and other control measures and to direct such efforts to areas that contribute substantially to recruitment of these species.…”

“…Limited knowledge of recruitment dynamics of Bighead and Silver carps in the Mississippi River basin, including river segments that represent the principal recruitment sources for these species, is an important source of uncertainty in predicting population responses to fishing and development of spatially explicit harvest and other potential control strategies (Tsehaye et al 2013). …”

Co-occurring bighead and silver carps show similar food preference but different isotopic niche overlap in different lakes

“…Studying feeding ecology of BC and SC is helpful to control fish yields depending on the trophic conditions of water bodies not only within China, but also worldwide where they play a major role in food security of rural people (Sugunan and Katiha 2004;Wijenayake et al 2005;Rahman et al 2012). Also, it is useful in places where these fish species should be managed in order to control either eutrophication levels of water bodies or protect indigenous species from invasion threats (Yang et al 2006;Ma et al 2010;Tsehaye et al 2013).…”

“…This practice has been followed in eutrophication control work as well (Chen et al 2006;Ke et al 2008). However, due to their rapid growth rate, efficient feeding habits, ability of adaptation to new environments and competition with native filter-feeders, they also have been considered as invasive species in some parts of the world, and subject to management accordingly (Chen et al 2006;Tsehaye et al 2013).…”