Growth and reproduction of female eastern and whitebelly spinner dolphins incidentally killed in the eastern tropical Pacific tuna purse-seine fishery

Larese, Jason P.; Chivers, Susan J.

doi:10.1139/z09-038

Cited by 15 publications

(26 citation statements)

References 21 publications

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“…dalli , S. attenuata, and S . longirostris was 197 cm, 181 cm, 166 cm, and 171.2, respectively [16,17,18,19]. In the absence of a direct measurement of LSM for D .…”

Section: Methodsmentioning

confidence: 99%

Validation of Blubber Progesterone Concentrations for Pregnancy Determination in Three Dolphin Species and a Porpoise

2013

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Recent studies have validated the use of biopsies as a minimally invasive way to identify pregnant females in several species of wild cetaceans: Balaenaptera acutorostrata , Delphinus delphis , Lissodelphis borealis , and Lagenorhynchus obliquidens . These studies found that progesterone (P4) concentrations quantified from blubber attached to biopsy samples is diagnostic of pregnancy. Here we examine a broader group of cetacean species in efforts to investigate how progesterone levels vary between species with respect to pregnancy status. We compared P4 concentrations in blubber collected from fishery bycatch and beach-stranded specimens for 40 females of known reproductive condition from Delphinus capensis (n = 18), Stenella attenuata (n = 8), S . longirostris (n = 6), and Phocoenoides dalli (n = 8). The P4 concentrations were different (t = -7.1, p = 1.79E-08) between pregnant and non-pregnant animals in all species, with the mean blubber P4 concentration for pregnant animals 164 times higher than that of non-pregnant animals. There was no overlap in concentration levels between sexually immature or non-pregnant sexually mature animals and pregnant animals. No significant differences (F = 0.354, p = 0.559) were found between mature non-pregnant and immature D . capensis and P dalli , suggesting P4 level is not indicative of maturity state in female delphinoids. P4 concentrations in relation to reproductive state were remarkably similar across species. All samples were analyzed with two different enzyme immunoassay kits to gauge assay sensitivity to measure progesterone in small samples, such as biopsies. With the technique now validated for these cetacean species, blubber P4 is a reliable diagnostic of pregnancies across multiple species, and thus expands the utility of this method to study reproduction in free-ranging cetaceans using biopsies.

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“…dalli , S. attenuata, and S . longirostris was 197 cm, 181 cm, 166 cm, and 171.2, respectively [16,17,18,19]. In the absence of a direct measurement of LSM for D .…”

Section: Methodsmentioning

confidence: 99%

Validation of Blubber Progesterone Concentrations for Pregnancy Determination in Three Dolphin Species and a Porpoise

2013

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“…For example, juveniles were over-represented in some studies of by-caught animals (stranded and retrieved directly from fishing vessels) (Kirkwood et al 1997, Siebert et al 2001, Jauniaux et al 2002, Jepson 2006, while in other studies they were under-represented (Delphinus delphis and Stenella longirostris by-catch in tuna purse-seine fisheries) (Danil & Chivers 2007, Larese & Chivers 2009). Male D. delphis have been over-represented in both Pacific and Atlantic fisheries (Ferrero & Walker 1995, Murphy 2004, Westgate & Read 2007, Danil et al 2010 and there are anecdotal reports that juvenile male bottlenose dolphins Tursiops truncatus on the US east coast are also over-represented.…”

Section: Signalmentmentioning

confidence: 99%

Criteria and case definitions for serious injury and death of pinnipeds and cetaceans caused by anthropogenic trauma

Moore¹,

Hoop²,

Barco³

et al. 2013

Dis. Aquat. Org.

136

140

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Post-mortem examination of dead and live stranded beach-cast pinnipeds and cetaceans for determination of a cause of death provides valuable information for the management, mitigation and prosecution of unintentional and sometimes malicious human impacts, such as vessel collision, fishing gear entanglement and gunshot. Delayed discovery, inaccessibility, logistics, human safety concerns, and weather make these events challenging. Over the past 3 decades, in response to public concern and federal and state or provincial regulations mandating such investigations to inform mitigation efforts, there has been an increasing effort to objectively and systematically investigate these strandings from a diagnostic and forensic perspective. This Theme Section provides basic investigative methods, and case definitions for each of the more commonly recognized case presentations of human interactions in pinnipeds and cetaceans. Wild animals are often adversely affected by factors such as parasitism, anthropogenic contaminants, biotoxins, subclinical microbial infections and competing habitat uses, such as prey depletion and elevated background and episodic noise. Understanding the potential contribution of these subclinical factors in predisposing or contributing to a particular case of trauma of human origin is hampered, especially where putrefaction is significant and resources as well as expertise are limited. These case criteria descriptions attempt to acknowledge those confounding factors to enable an appreciation of the significance of the observed human-derived trauma in that broader context where possible.

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“…1), which is similar to the pattern observed for another delphinid species, bottlenose dolphins (Noren et al, 2001). Nonetheless, a body length of 141 cm corresponds to spinner dolphins that are ∼1.6-2.0 years old [age estimate based on a length-at-age relationship for spinner dolphins; Larese and Chivers, 2009] and since spinner dolphins are weaned at 1.3-1.6 years postpartum (Evans, 1987), maturation of the muscle biochemistry examined in this study occurs after the age of weaning. Likewise, the maturation of the muscle buffering capacity and myoglobin content of bottlenose dolphins occurs after the age of weaning (Table 3).…”

Section: Discussionmentioning

confidence: 99%

“…The selection of the best breakpoint and function type was based on maximizing the statistical coefficient of explanation, and performing tests of significance across seven types of functions (www.waterlog.info/ pdf/regtxt.pdf ). With knowledge of the body length at which muscle biochemistry matured, we could estimate the age at which muscle biochemistry matured from parameter value estimates for length-atage relationships for eastern spinner dolphins (S. l. orientalis; table 4 in Larese and Chivers, 2009). We used a length-at-age relationship for a different subspecies of spinner dolphin because a length-at-age relationship has not been determined for S. l. longirostris.…”

Section: Statisticsmentioning

confidence: 99%

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Muscle biochemistry of a pelagic delphinid (Stenella longirostris longirostris): insight into fishery-induced separation of mothers and calves

Noren

West

2017

Journal of Experimental Biology

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The length of time required for postnatal maturation of the locomotor muscle (longissimus dorsi) biochemistry [myoglobin (Mb) content and buffering capacity] in marine mammals typically varies with nursing duration, but it can be accelerated by species-specific behavioral demands, such as deep-diving and sub-ice transit. We examined how the swimming demands of a pelagic lifestyle influence postnatal maturation of Mb and buffering capacity in spinner dolphins (Stenella longirostris longirostris). Mb content of newborn (1.16±0.07 g Mb per 100 g wet muscle mass, n=6) and juvenile (2.77±0.22 g per 100 g, n=4) spinner dolphins were only 19% and 46% of adult levels (6.00± 0.74 g per 100 g, n=6), respectively. At birth, buffering capacity was 52.70±4.48 slykes (n=6) and increased to 78.53±1.91 slykes (n=6) once a body length of 141 cm was achieved, representing 1.6-to 2.0-year-old dolphins. Based on the age of weaning (1.3-1.6 years postpartum), muscle maturation occurred just after weaning as described for coastal bottlenose dolphins (Tursiops truncatus). Thus, a pelagic lifestyle does not promote rapid maturation of muscle biochemistry. Rather, it promotes enhanced muscle biochemistry: newborn and adult spinner dolphins had four-and two-times greater Mb contents than newborn and adult bottlenose dolphins, respectively. Indeed, adult levels rivaled those of deep-diving cetaceans. Nonetheless, the relatively underdeveloped muscle biochemistry of calves likely contributes to documented mother-calf separations for spinner dolphins chased by the tuna purse-seine fishery.

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Growth and reproduction of female eastern and whitebelly spinner dolphins incidentally killed in the eastern tropical Pacific tuna purse-seine fishery

Cited by 15 publications

References 21 publications

Validation of Blubber Progesterone Concentrations for Pregnancy Determination in Three Dolphin Species and a Porpoise

Validation of Blubber Progesterone Concentrations for Pregnancy Determination in Three Dolphin Species and a Porpoise

Criteria and case definitions for serious injury and death of pinnipeds and cetaceans caused by anthropogenic trauma

Muscle biochemistry of a pelagic delphinid (Stenella longirostris longirostris): insight into fishery-induced separation of mothers and calves

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