Hook‐shaped enterolith and secondary cachexia in a free‐living grey nurse shark ( Carcharias taurus, Rafinesque 1810)

Underwater stereo-video photogrammetry was used to document the pectoral fin positions of various life-history stages of the critically endangered east Australian population of the grey nurse shark (Carcharias taurus) during normal swimming behaviour at multiple aggregation sites. A wide range in pectoral fin positions was recorded with dihedral pectoral fin angles ranging from –25 to 88°. Pectoral fin angles varied significantly among sites and this was attributed to the differing navigational and energetic requirements of the sharks. There was no significant relationship between pectoral fin angles and distances separating the shark and scuba diver. The wide range in pectoral fin angles, interactive use of the fins during swimming, low-energy behaviours of the sharks at aggregation sites and absence of ‘fight’ response agonistic behaviour indicated that the species does not exhibit agonistic pectoral fin depression. Reports of agonistic pectoral fin depression in the grey nurse shark obtained with visual estimates should be treated as preliminary observations requiring further testing using accurate sampling methods such as stereo photogrammetry. It is important that diver compliance with existing management guidelines that prohibit divers from chasing or harassing grey nurse sharks and blocking cave and gutter entrances is maintained.

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Nuclear and mitochondrial DNA reveals isolation of imperilled grey nurse shark populations (Carcharias taurus)

Molecular Ecology ◽

10.1111/j.1365-294x.2009.04377.x ◽

2009 ◽

Vol 18 (21) ◽

pp. 4409-4421 ◽

Cited By ~ 58

Author(s):

H. AHONEN ◽

R. G. HARCOURT ◽

A. J. STOW

Keyword(s):

Mitochondrial Dna ◽

Nurse Shark ◽

Carcharias Taurus

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Impacts of recreational fishing in Australia: historical declines, self-regulation and evidence of an early warning system

Environmental Conservation ◽

10.1017/s0376892914000046 ◽

2014 ◽

Vol 41 (4) ◽

pp. 350-356 ◽

Cited By ~ 16

Author(s):

MATTHEW A. L. YOUNG ◽

SIMON FOALE ◽

DAVID R. BELLWOOD

Keyword(s):

Early Warning System ◽

Self Regulation ◽

Warning System ◽

Vital Role ◽

Recreational Fishing ◽

Recreational Fisheries ◽

Nurse Shark ◽

Governance Challenges ◽

The Impact ◽

Carcharias Taurus

SUMMARYOverfishing is a mounting threat to marine ecosystems and food security worldwide. Recreational fisheries are poorly understood and pose governance challenges due to the scarcity of monitoring data. The impact of recreational spearfishing on eastern blue groper (Achoerodus viridis) and grey nurse shark (Carcharias taurus) in Australia was analysed by assessing a chronology of spearfishing publications for historical, ecological and social data. Reported captures of blue groper declined by 90% from 1952–1967. Grey nurse shark captures also declined. Interestingly, early warnings of declines for both species emerged from the spearfishing community 17 and 19 years, respectively, before protection. While recreational fishers may have serious impacts on vulnerable fish species, they could also play a vital role in conservation and advocacy. This highlights the importance of reciprocal communication between fishers, scientists and governments for managing and detecting declines in vulnerable species.

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