Cookie‐cutter shark Isistius spp. predation upon different tuna species from the south‐western Atlantic Ocean

Abstract

The predation of cookie-cutter sharks Isistius spp. upon the early life stages of yellowfin tuna Thunnus albacares, skipjack tuna Katsuwonus pelamis and little tunny Euthynnus alletteratus are described. New evidence suggesting a connection between commercial fishing and predation by Isistius sp. is presented, with these sharks biting tunas hooked in surface waters during daylight. The healing patterns of the wounds made by the sharks are described in detail and, although such damage is known to negatively influence market price elsewhere, it is not the case on the south-east Brazilian coast.

Recommendations towards the establishment of best practice standards for handling and intracoelomic implantation of data-storage and telemetry tags in tropical tunas

“…We recognize, however, that tonic immobilization does not induce loss of sensation [91], but argue that its benefits associated with the reduced stress associated with rapid return to the water supersede the impracticalities of anesthesia or sedation. Our field observations indicate, moreover, that the incisions required for BCT implantation are equivalent to, or less than, non-lethal predation damage observed in larger tunas and billfishes [69,72].…”

Simulating cookiecutter shark bites with a 3D-printed jaw-dental model

“…3), and for bites that were less than the maximum gape there would be an inconsistent number of reference points needed to fully assess warp. In addition to the simulated bite experiment, other studies support the lack of validity for I. plutodus versus I. brasiliensis bite attributions to species based on bite wound geometrics (Best and Photopoulou 2016, Feunteun et al 2018, Niella et al 2018, Menezes et al 2022).…”

An equatorial mid‐Atlantic Ocean archipelago as nursery area for the cookiecutter shark: Investigating foraging strategies of neonates through bite mark inferences

“…The bite marks were categorized into seven healing stages adapted from Niella et al (2018): (1) recently bitten, (A) fresh (marks still con- individual fish and their diameters were measured. In addition, a scale was developed to properly identify the part of the body (ventral, bite marks found by the pectoral and anal fins; lateral, bite marks found around the lateral line; or dorsal, bite marks found by the dorsal fin) of cookiecutter shark preference by fish species.…”

“…In addition, most of the fish species examined exhibited single bite marks, with the exception of wahoo, which had the highest incidence of multiple bites, with some individuals showing up to 10 wounds. These multiple bites could be the result of either one shark inflicting numerous bites or several sharks each delivering a single bite (Niella et al, 2018). It is essential to consider that the higher frequency of bite marks on wahoo might be influenced by the fishing gear used in the study, rather than a specific preference of the cookiecutter shark for wahoo.…”

“…and the potential underestimation of scars due to their resemblance to skin color (Niella et al, 2018). Despite these constraints, the pre-…”