Comparative Biochemistry and Physiology, Part A 162 (2012) 121–129 Contents lists available at SciVerse ScienceDirect Comparative Biochemistry and Physiology, Part A journal homepage: www.elsevier.com/locate/cbpa Hematological indicators of stress in longline-captured sharks☆ Heather Marshall a,⁎, Lyndsay Field a,1, Achankeng Afiadata a, Chugey Sepulveda b, Gregory Skomal c, Diego Bernal a,⁎ a University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA b Pfleger Institute of Environmental Research, 315 North Clementine, Oceanside, CA 92054, USA c Massachusetts Division of Marine Fisheries, 838 South Rodney French Boulevard, New Bedford, MA 02744, USA article info abstract Article history: For many shark species, little information exists about the stress response to capture and release in commer- Received 13 August 2011 cial longline fisheries. Recent studies have used hematological profiling to assess the secondary stress re- Received in revised form 2 February 2012 sponse, but little is known about how, and to what degree, these indicators vary interspecifically. Accepted 7 February 2012 Moreover, there is little understanding of the extent to which the level of relative swimming activity (e.g., Available online 14 February 2012 sluggish vs. active) or the general ecological classification (e.g., coastal vs. pelagic) correlates to the magni- Keywords: tude of the exercise-induced (capture-related) stress response. This study compared plasma electrolytes + − 2+ 2+ + Biochemistry (Na ,Cl ,Mg ,Ca , and K ), metabolites (glucose and lactate), blood hematocrit, and heat shock protein Bycatch (Hsp70) levels between 11 species of longline-captured sharks (n=164). Statistical comparison of hemato- Elasmobranch logical parameters revealed species-specific differences in response to longline capture, as well as differences Fisheries by ecological classification. Taken together, the blood properties of longline-captured sharks appear to be Longline useful indicators of interspecific variation in the secondary stress response to capture, and may prove useful in the future for predicting survivorship of longline-captured sharks where new technologies (i.e., pop-up satellite tags) can verify post-release mortality. © 2012 Elsevier Inc. All rights reserved. 1. Introduction Fish react to capture and handling with more exaggerated physio- logical responses than most other higher vertebrates (reviewed by In recent decades, the interaction between sharks and fishing gear Skomal and Bernal, 2010; Skomal and Mandelman, 2012) and the has increased, and these fish now account for a large percentage stress response has been classified into three levels: primary, second- of incidental bycatch in pelagic commercial fisheries worldwide ary, and tertiary (Mazeaud et al., 1977). Like teleosts, sharks exhibit (Beerkircher et al., 2002; Gilman et al., 2008; Skomal and Bernal, primary and secondary responses to stress that are manifested in 2010). It is estimated that elasmobranchs, although rarely targeted, their blood biochemistry (reviewed by Skomal and Bernal, 2010; constitute 25% of the overall catch in U.S. commercial longline fisher- Skomal and Mandelman, 2012). Recently, stress responses in fish ies (Mandelman et al., 2008) and comprise as much as 94% of total by- have been shown to vary interspecifically and may be linked to: 1) catch in commercial longline operations worldwide (McKinnell and a fish's metabolic scope and its cruise/burst swimming capacity, 2) Seki, 1998). The commercial value of sharks is often low and certain the ability to physiologically respond to stress, and 3) the capacity species (e.g., dusky shark, Carcharhinus obscurus) are mandated to to recover from the stressor (Mandelman and Skomal, 2009; Skomal be released in an effort to reduce fishing mortality (NMFS, 2008). and Bernal, 2010). Indeed, at-vessel mortality data from commercial Therefore, the release of longline-captured sharks has become a com- fisheries and research surveys show that shark species respond differ- mon practice (Skomal, 2007; Mandelman et al., 2008; Skomal and ently to capture by the same fishing gear (e.g., Beerkircher et al., Bernal, 2010). 2002; Morgan and Burgess, 2007; Mandelman and Skomal, 2009; Morgan and Carlson, 2010). ☆ “ Given the increasing number of sharks released from commercial This paper stems from a presentation in the symposium The Physiological Stress fi Response in Elasmobranch Fishes,” at the 26th annual meeting of the American Elas- longline gear and the potential interspeci c variation in response to mobranch Society, held on July 11, 2010, in Providence, Rhode Island (USA). longline capture, the objective of the current study was to determine ⁎ Corresponding authors at: University of Massachusetts Dartmouth, Biology Depart- if blood samples can be used to characterize and compare the second- ment, 285 Old Westport Road, North Dartmouth, MA, 02747, USA. Tel.:+508 999 8307; ary stress response in several species of sharks exposed to longline fax: +508 999 8196. capture. Due to the challenges associated with keeping many of E-mail addresses: [email protected] (H. Marshall), [email protected] (D. Bernal). these large sharks in captivity, such stress parameters have not 1 The author is deceased. been published before and we hope these preliminary data will be a 1095-6433/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.cbpa.2012.02.008 122 H. Marshall et al. / Comparative Biochemistry and Physiology, Part A 162 (2012) 121–129 starting point for future stress physiology research on sharks having Rad protein ladder to determine the proper separation of the different levels of swimming activity (e.g., sluggish vs. active swim- ~70 kDa band and to verify the position of an Hsp standard (Sigma mers), and inhabiting ecologically distinct areas (e.g., coastal waters Aldrich, St. Louis MO, USA). Proteins were transferred onto a PVDF- that are relatively shallow [b80 m] and well-mixed vs. the deep fluorescent membrane (Millipore, Billerica, MA USA) and stained [>200 m] and well-stratified pelagic environment). In addition to with a primary antibody against Hsp70 (Agrisera AS05-083) followed commonly used blood parameters, we investigated the use of heat by a fluorescent secondary antibody (Li-Cor IRDye680) and detected shock proteins (Hsps) as potential indicators of the stress response by a Li-Core Odyssey Infrared Imaging System (version 3.0.16). The in sharks. We also examined the extent to which the published at- Hsp70 levels in each species were compared by normalizing the signal vessel mortality rates for these species (Beerkircher et al., 2002; of the blue shark (Prionace glauca), therefore providing relative levels Yokota et al., 2006; Morgan and Burgess, 2007; Morgan and Carlson, of Hsp70 between species. Work on blue sharks has shown this spe- 2010) may be related to the magnitude of the stress response. cies to have low at-vessel mortality rates (Yokota et al., 2006) and a relatively high post-release survival (Moyes et al., 2006). For this rea- 2. Materials and methods son, we selected the blue sharks as the benchmark of a low-stress condition (verified by the values of other blood stress parameters in 2.1. Sampling the present study). Fresh blood samples were collected from 2006 to 2009 during 2.5. Statistical analysis NOAA/NMFS longline research cruises assessing fish abundance fi [western Paci c ocean (WPO): R/V Oscar Elton Sette, 2008; eastern Although our goal was to sample a large number of species, the fi North Paci c ocean (ENP): R/V David Starr Jordan, 2007; western sample sizes for each species were limited by our catch. For this rea- North Atlantic (WNA): R/V Delaware II, 2007, 2009 and F/V Eagle son, even species with a low sample size were included in the inter- Eye II, 2006]. Two types of longline gear were used (demersal and pe- specific comparisons. “ ” lagic) with different overall soak times (i.e. time period that the line A general linear model univariate analysis of variance (ANOVA) fi is shing) and hook types (circle vs. J hooks). For demersal sets, circle was used to determine how blood parameters varied by species and – hooks were suspended at or near the bottom (30 60 m) and soaked family, and two-sample T-tests were used to detect differences by – for 2 6 h, and for pelagic sets, circle and J hooks were suspended ecological classification (i.e., pelagic versus coastal association) and – within the upper 150 m of the water column and soaked for 4 12 h. between moribund and non-moribund shortfin mako sharks (the fi Unfortunately, the inherent logistical dif culties of working on nu- only species with moribund specimens) (Sokal and Rohlf, 1995). As- fi merous vessels with varying scienti c agendas did not allow for the sumptions were satisfied using Levene's test of homogeneity of vari- deployment of hook timers to measure time on the line. Longlines, re- ances and a visual examination of the data for normality, and Tukey gardless of type, were set at sea surface temperatures ranging from 17 post-hoc tests were performed to compare values between groups. to 24 °C. Immediately after capture, sharks were brought on the boat Regression analyses (Sokal and Rohlf, 1995) were used to deter- – and blood samples (2 10 mL) were collected via caudal puncture mine if at-vessel mortality rates were related to blood stress parame- using an 18-gauge needle and heparinized syringe. Blood samples ters. Because each species in this study was caught in only one body were kept at 4 °C until processing, which occurred mostly 2 to of water (e.g., the sandbar sharks were only caught in the WNA and 4 min after capture, but in some cases were up to an hour after cap- mako sharks were only captured in the ENP), intraspecific differences ture. Blood was also sampled from moribund sharks, but no blood due to geography were ruled out. Species-, gear- (i.e., pelagic vs. de- was taken from dead specimens.