Mortality due to a retained circle hook in a longfin mako shark Isurus paucus (Guitart‐Manday)

Abstract

A female longfin mako shark Isurus paucus (Guitart-Manday, 1966) was found moribund on the Atlantic Ocean beach near Canaveral National Seashore, Florida; the shark died shortly after stranding. Macroscopic lesions included a partially healed bite mark on the left pectoral fin, a clefted snout, pericardial effusion and a pericardial mass surrounding a 12/0 circle fishing hook. The heart, pericardial mass, gills, ovary, oviduct, shell gland, epigonal organ, liver, kidney and intrarenal and interrenal glands were processed for histopathology and examined by brightfield microscopy. Microscopic examination revealed chronic proliferative and pyogranulomatous pericarditis and myocarditis with rhabdomyolysis, fibrosis and thrombosis; scant bacteria and multifocal granular deposits of iron were found intralesionally. In addition, acute, multifocal infarcts within the epigonal organ and gill filaments were found in association with emboli formed by necrocellular material. The ovary had high numbers of atretic follicles, and the liver had diffuse, severe hepatocellular degeneration, multifocal spongiosis and moderate numbers of melanomacrophage cells. This report provides evidence of direct mortality due to systemic lesions associated with retained fishing gear in a prohibited shark species. Due to the large numbers of sharks released from both recreational and commercial fisheries worldwide, impact of delayed post-release mortality on shark populations is an important consideration.

Meta‐analysis of post‐release fishing mortality in apex predatory pelagic sharks and white marlin

“…Moreover, it appears F r outcomes could eventuate after several months. Hooks lodged in the oesophagus or stomach can penetrate the body cavity causing chronic proliferative responses resulting in opportunity for bacterial or algal infection, inflammation, systemic infection and possible death over the course of several months (Adams, Borucinska, Maillett, Whitburn & Sander, ; Borucinska, Kohler, Natanson & Skomal, ; Borucinska, Martin & Skomal, ).…”

High survivorship after catch-and-release fishing suggests physiological resilience in the endothermic shortfin mako shark (Isurus oxyrinchus)

“…Necropsy has shown foul hooking to be associated with hook penetration of the pericardium ( Kneebone et al , 2013 ) and vital organs such as the heart, liver and parts of the lower alimentary canal ( Caruso, 2000 ; Borucinska et al , 2001 , 2002 ). Retained hooks can also lead to mortality over longer periods by causing systemic diseases ( Borucinska et al , 2001 ; Adams et al , 2015 ). The significant reduction in foul hooking that we observed with circle hook use is in agreement with the findings of many other authors ( Caruso, 2000 ; Cooke and Suski, 2004 ; Bartholomew and Bohnsack, 2005 ; Mapleston et al , 2008 ; Pacheco et al , 2011 ).…”

A review of capture and post‐release mortality of elasmobranchs

“…It is important to recognize that discard mortality encompasses both AVM and PRM, where a proportion of those fishes discarded alive may die in the short-term as a consequence of any physical injury, trauma and physiological stress sustained during capture and handling (Pollock & Pine, 2007;Poisson et al, 2014a). Injured fishes may also be prone to infection (Borucinska et al, 2002;Adams et al, 2015), more susceptible to attack by predators and scavengers (Davis, 2002) or have sustained physiological damage that may affect the feeding and swimming behaviour, growth, the immune system or reproductive biology (Skomal, 2007), even over the longer term. An increasing number of studies have used a combination of approaches so that AVM and PRM can be assessed, but it should also be remembered that some of these methods (e.g.…”