The Devil is in the Detail: Photo‐Identification Reveals Novel Information on the Biology of a Temperate Reef Fish, the Southern Blue Devil ( Paraplesiops meleagris )

Abstract

A photo‐identification technique based on the unique detail of the head markings of individual fish was developed and utilised in a long‐term (>10 years) study at four discrete populations of the southern blue devil ( Paraplesiops meleagris ), a small demersal fish endemic to Australia's Great Southern Reef (GSR). The study revealed novel information on its life history and behaviour, including that population sizes were relatively small and dominated by larger fish, juvenile recruitment was infrequent and the larger fish displayed relatively slow growth rates, longevity, high site fidelity, territorial behaviour and small home ranges. Several fish were photo‐recaptured after 14 years with one fish after 18 years. Breeding occurred during the Austral summer, whereby an adhesive egg mass was laid on the ceiling of a cave or ledge and guarded by the male until the eggs hatched into free swimming planktonic larvae. Paraplesiops meleagris has a combination of life history and behavioural traits which renders it vulnerable to localised population depletions from which it may take a long time to recover. These traits also mean that no‐take marine protected areas will be an effective conservation tool and that it could be a sentinel species for monitoring changes in the GSR.

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