Plasma catecholamine levels as indicators of the post-release survivorship of juvenile pelagic sharks caught on experimental drift longlines in the Southern California Bight

Abstract

Between 1983 and 2004, nearly 12 000 shortf in mako (Isurus oxyrinchus), common thresher (Alopias vulpinus) and blue (Prionace glauca) sharks were tagged in the Southern California Bight; however, only 1.97% of these have been returned. One possible reason for this low return rate could be post-release mortality caused by capture stress from the experimental longline. Plasma catecholamine levels were analysed to evaluate stress levels in longline-captured, rod-and-reel-captured and unstressed docile sharks. The mean catecholamine values determined for the three tag–release species ranged from 6539 to 22 079 pg mL–1. The level of adrenaline found in moribund I. oxyrinchus (94 807 pg mL–1) was much higher than in either P. glauca (46 845 pg mL–1) or A. vulpinus (36 890 pg mL–1). In contrast, blood obtained from sharks that were landed within minutes had lower catecholamine values (P. glauca, 889 and 1347 pg mL–1; I. oxyrinchus, 2960 and 3946 pg mL–1, adrenaline and noradrenaline respectively). Among the nine I. oxyrinchus specimens that were recaptured long after their longline capture and release, the highest adrenaline level measured just before release was 33 352 pg mL–1. Because these mako sharks survived sufficiently long to be recaptured, their time-of-release catecholamine levels provide a conservative estimate of ~80% viability on the longline-captured and released population.

Retained fishing gear and associated injuries in the east Australian grey nurse sharks (Carcharias taurus): implications for population recovery

“…While there is evidence that indicates the short-term survival rate of released sharks can be high (Gurshin and Szedlmayer 2004;Moyes et al 2006;Hight et al 2007), these studies do not address the issue of longer-term mortality that may result from ingested hooks and associated disease. Peritonitis, intra-lesional bacteria and cachexi have been observed in blue sharks, Prionace glauca, with retained hooks (Borucinska et al 2001(Borucinska et al , 2002.…”

Moving from Measuring to Predicting Bycatch Mortality: Predicting the Capture Condition of a Longline-Caught Pelagic Shark

“…Although, measuring these two variables was out of the scope of the present study, intramuscular lactate and plasma catecholamine may be good predictors of shark mortality following capture (Hight et al, 2007;Frick et al, 2012). Additional information on how these variables can influence capture condition can be used to determine the biological systems that are most detrimentally effected by fisheries capture and can help to design effective management strategies.…”

“…For example, if the likelihood of mortality increases with increasing sea surface temperature, temporal restrictions on fishing during some months could be enacted to reduce bycatch mortality. Predictive models can also be used to identify physiological thresholds at which immediate and post-release mortality are likely to occur (Moyes et al, 2006;Hight et al, 2007;Frick et al, 2010).…”

Evaluation and use of a portable field kit for measuring whole-blood lactate in sharks

“…Previous studies have reported both whole-blood and plasma lactate concentrations .23.3 mmol L À1 (the upper limit for the Lactate Pro) in several species of sharks, including Isurus oxyrinchus and Alopias vulpinus (Hight et al 2007), Prionace glauca (Moyes et al 2006), Rhizoprionodon terraenovae (Hoffmayer and Parsons 2001), Carcharhinus obscurus (Cliff and Thurman 1984;Mandelman and Skomal 2009) and C. plumbeus (Brill et al 2008). In the present study, diluting the whole-blood by 50%, whether using acidified saline, tap water or distilled water, provided a simple and reliable method for measurement of potentially off-scale lactate concentrations.…”

“…The relatively unique characteristics of elasmobranch blood -nucleated red blood cells and high levels of nitrogen products (Lai et al 1997) -make it essential that such testing occurs. In addition, because sharks can have whole-blood and plasma lactate levels .40 mmol L À1 (Hoffmayer and Parsons 2001;Hight et al 2007;Brill et al 2008), which is greater than the range of human values, and, hence, the range of the portable analyser, a method for addressing values higher than the upper detection limit is needed.…”