Non-lethal assessment of the reproductive status of broadnose sevengill sharks (Notorynchus cepedianus) to determine the significance of habitat use in coastal areas

Awruch, Cynthia A.; Jones, Susan; Asorey, Martin García; Barnett, Adam

doi:10.1093/conphys/cou013

Cited by 35 publications

(27 citation statements)

References 42 publications

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“…The latter could be related to the biennial reproductive cycle of females. During spring/summer, individual females can be either ready to ovulate, in final stages of gestation, or in postparturition, whereas during autumn/winter they can be in early stages of follicular development or gestating (Awruch et al 2014). Immune and health-related parameters were mostly independent of reproductive hormone concentrations at the individual level, a result similar to that documented for a free-living teleost fish (Vainikka et al 2004).…”

Section: Discussionsupporting

confidence: 73%

“…On the other hand, only one negative association between testosterone levels and lymphocyte counts during spring/ summer was found for females. The latter could be seen as consistent with an immunosuppressive effect of testosterone on adaptive immunity of females during the reproductive period; however, this interpretation is unclear at present given the poorly understood role of female androgens in shark reproduction (Awruch et al 2014). Overall, this study provides little support for a trade-off between immunity and reproduction in this system.…”

Section: Discussionmentioning

confidence: 82%

“…Plasma levels of E 2 , P 4 , and T were measured in both sexes by radioimmunoassay following Awruch et al (2014). Briefly, testosterone antiserum was reconstituted by diluting 1∶10 in PBS containing 0.1% gelatin and 0.01% thiomersal.…”

Section: Reproductive Hormone Measurementsmentioning

confidence: 99%

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Seasonality of Immunological and Health-State Parameters of Wild Broadnose Sevengill Shark,Notorynchus cepedianus

Sueiro

Awruch

Irigoyen

et al. 2019

Physiological and Biochemical Zoology

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Seasonal fluctuation in environmental parameters can influence immune responses of vertebrates and consequently influence their health and disease resistance. Although seasonality of immune function is well documented in a broad range of vertebrate taxa, this information remains virtually unexplored in cartilaginous fish. Here we examine seasonal variation in immune and general-health parameters of freeliving adult broadnose sevengill sharks, Notorynchus cepedianus, along an annual cycle. We sampled sharks during autumn/winter (i.e., coolest temperatures and nonreproductive period) and spring/summer (i.e., warmest temperatures and active reproductive period) and assessed aspects of immunity, general condition, and reproductive hormone levels. A seasonal influence was observed in some, but not all, parameters evaluated. Lower lymphocyte counts and higher heterophil counts and granulocyte to lymphocyte (G∶L) ratios were observed in sharks sampled during autumn/winter than in those sampled during spring/summer. On the other hand, total leukocyte counts, eosinophil counts, bacterial agglutination mediated by natural antibodies, and hematocrit did not vary seasonally. The observed seasonal patterns could be explained as (1) greater levels of stress based on the G∶L ratio, (2) a sign of immunosuppression or depressed immune investment based on the low lymphocyte counts, and/or (3) a sign of ongoing infection based on the higher heterophil counts in the colder seasons with respect to the warmer ones. In addition, the pattern is in line with the notion that while acquired components are usually depressed by lower temperatures, some innate components might increase to offset that reduction. Immune and health-state parameters were mostly independent of reproductive hormone levels, providing little support for a trade-off with reproduction. Overall, the observed seasonal pattern in immunity of broadnose sevengill sharks could be related to changes in abiotic environmental condition, such as water temperature and photoperiod, although other factors such as availability of high-quality food may play a part.

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 82%

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Seasonality of Immunological and Health-State Parameters of Wild Broadnose Sevengill Shark,Notorynchus cepedianus

Sueiro

Awruch

Irigoyen

et al. 2019

Physiological and Biochemical Zoology

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“…Tritiated T [1,2,6,7‐ 3 H], E 2 [1,2,6,7‐ 3 H] and P 4 [1,2,6,7‐ 3 H] were purchased from Perkin‐Elmer (Melbourne, VIC, Australia) and 50 μl of each was diluted in 5 ml of 100% ethanol and kept as separate stock for the assay. The assay protocol used was as described by Awruch, Jones, Asorey, and Barnett (). Briefly, plasma samples (200 μl) were extracted twice with ethyl acetate (1 ml), and two 100 μl aliquots were transferred to assay tubes.…”

Section: Methodsmentioning

confidence: 99%

Identification of essential habitats: Including chimaeras into current shark protected areas

Barnett

McAllister²,

Semmens³

et al. 2019

Aquatic Conservation

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1. Essential habitats are areas required to support specific functions, such as providing foraging grounds, shelter or used for reproductive purposes. For mobile aquatic species that move throughout numerous components of the seascape, identifying essential habitats within a species' broader distribution range is crucial to understanding their ecology and provide vital information needed to underpin effective conservation and management (e.g. the implementation of protected areas). 2. In Tasmania (Australia), a number of coastal habitats have been declared shark refuge areas (SRAs), where fishing for elasmobranchs (sharks, rays and skates) is prohibited.3. Chimaeras are relatives of elasmobranchs (class Chondrichthyes) and share traits that predispose many elasmobranch species to be vulnerable to overfishing (e.g. slow growth rates and low reproductive output). However, fishing for elephantfish Callorhinchus milii (the chimaera species found in coastal Tasmania) is still permitted in SRAs. 4.Here, a combination of acoustic tracking, catch data and reproductive information was used to determine the significance of the SRA coastal habitats for C. milii. 5.Results suggest that these areas are essential habitats for reproduction and likely important for other purposes, such as foraging. 6. Given that a key strategy in managing fish stocks is protecting areas important for reproduction, and the importance of these coastal areas of Tasmania for C. milii reproductive purposes, we recommend including C. milii in current SRAs, and decreeing these areas as chondrichthyan refuge areas.

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“…The success of the tissue sampling program demonstrates that citizen science can be utilised for non-lethal sampling of recreationally-caught fish. Given that researchers have applied non-lethal sampling for studies on such factors as diet (Jardine et al, 2011), heavy metal contamination (Lake et al, 2006) and reproductive biology (Awruch et al, 2014), the success of this program promotes the possibility of citizen scientists assisting with the collection of biological samples for future research in the aforementioned fields. While the technique used herein was non-lethal and minimally-invasive, there may also be scope for future investigations to explore less invasive methods such as the collection of surface mucus as noted by Hoolihan et al (2009).…”

Section: Discussionmentioning

confidence: 99%

The global biology, ecology and phylogenetic status of black marlin (Istiompax indica)

Williams¹

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The black marlin [Istiompax indica (Morrow, 1968)] is one of the largest teleost fish and has a continuous distribution throughout tropical waters of the Indo-Pacific. Throughout its range, I. indica has been documented to undertake wide-ranging, transoceanic and transequatorial movements. In coastal waters and on the high seas I. indica may be targeted by commercial and artisanal fisheries, but the majority of the world's landings are as a by-product species of tuna longline and purse seine fisheries. Due to its large size and 'fighting qualities', I. indica is also valued as a prized sport or game fish in recreational fisheries. While considerable effort to understand the level of exploitation of high value species such as the tunas has occurred, the stock status for many other species caught on the high seas such as many sharks, dolphinfish and istiophorid billfishes remain unassessed. This lack of attention is reflected by I. indica being listed as 'Data Deficient' on the International Union for Conservation of Nature Red List. The lack of attention and data available on I. indica extends to biological, ecological, taxonomic and fisheries catch records, which in turn hinders stock assessments and management. This thesis aims to improve the biological and ecological knowledge of I. indica, thereby providing a stronger foundation for assessments and management of stocks globally. PUBLICATIONS DURING CANDIDATURE Peer-reviewed papers and book chaptersA Cohen, D. Spooner and SM. Williams (In Press). Examining the importance of marine transport and transport infrastructure and the initiatives adopted for managing potential impacts whilst enhancing transport services. Moreton Bay and Catchment.

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Non-lethal assessment of the reproductive status of broadnose sevengill sharks (Notorynchus cepedianus) to determine the significance of habitat use in coastal areas

Cited by 35 publications

References 42 publications

Seasonality of Immunological and Health-State Parameters of Wild Broadnose Sevengill Shark,Notorynchus cepedianus

Seasonality of Immunological and Health-State Parameters of Wild Broadnose Sevengill Shark,Notorynchus cepedianus

Identification of essential habitats: Including chimaeras into current shark protected areas

The global biology, ecology and phylogenetic status of black marlin (Istiompax indica)

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