Relationship Between Angling Pressure and the Prevalence of Neascus spp. in Bluegill

Maple, A.P. and K.L. Pope.  2011.  Relationship between Angling Pressure and the Prevalence of Neascus spp. in Bluegill. 141^st Annual Meeting of the American Fisheries Society, Seattle, Washington.  Poster Presentation.

Recreational angling (i.e. catch-and-release) is increasing in popularity throughout regions of the USA.  A majority of states agencies have catch-and-release programs promoting recreational angling on public waterbodies.  Although catch-and-release angling is ultimately a tool used to benefit an over-exploited fishery, fish are stressed by extreme angling pressure that is often facilitated by catch-and-release programs.  Changes in fish behavior, physiology, and fitness of fish can be caused by an extended angling event and long air exposure.  When stress compromises the immune system, fish become more susceptible to parasites, especially larval trematodes (i.e. Neascus spp.) that are visible to the naked eye.  Thus, a positive relationship likely exists between angling pressure, a surrogate assessment to stress caused by catch-and-release events, and parasite prevalence.  We surveyed fifteen Salt Valley reservoirs in Nebraska on which catch-and-release angling was the most popular form of angling to determine if a positive relationship exists between angling pressure and Neascus spp. prevalence in bluegill.  As expected, positive relationships exist between parasite prevalence and fish age and between parasite prevalence and total length.  Contrary to our a prior prediction, there was not a positive relationship between angling pressure and parasite prevalence; even so, three distinct groupings were evident for these reservoirs that likely result from an interplay between angling pressure and parasite prevalence.  It is probable that several factors play a role in parasite prevalence (e.g. extreme temperature, surrounding habitat), including the possible existence of a negative feedback loop in the relationship between angling pressure and parasite prevalence in which anglers avoid fishing reservoirs where they perceive parasite infestations are problematic.