Guest Comment: List shark under Endangered Species Act

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Conservation organizations Defend Them All Foundation and the Center for Biological Diversity have submitted a petition to the National Marine Fisheries Service asking for the protection of the tope shark (Galeorhinus galeus) under the United States Endangered Species Act, including the designation of critical habitat for the species in United States waters.

West Coast breeding sites such as La Jolla are critical to the survival and recovery of the top shark due to the species’ tendency to occupy warmer waters to incubate their embryos to minimize the gestation period of 12 months of sharks. Studies suggest that puppies stay in their nursery for up to two years.

The tope shark, also known as the soup shark, is long and slender, up to 6½ feet long and nearly 100 pounds, has a late sexual maturity of about 12½ years, and lives up to 60 years. Tope sharks are known for their large-scale seasonal migrations that cross multiple state and/or national borders.

The International Union for Conservation of Nature has classified the great shark as critically endangered due to a steep 88% decline in the species’ global population over the past 79 years, mostly due to due to overfishing. The slow rate of maturation of sharks and their tendency to swim in schools separated by sex and age make them vulnerable to overexploitation, as multiple sharks from the same school can be caught simultaneously, often inhibiting reproduction by suppressing breeding members of the species. For example, most topsharks found in southern California are female, while males predominate from northern California to British Columbia.

While fishing pressures and accidental capture as bycatch are the main threats to the species, habitat degradation, climate change and inadequate regulatory mechanisms are other factors driving the species to the ‘extinction.

Fishing and bycatch

Despite a clear international consensus that sharks should be protected globally, sharks – including the great shark – continue to be exploited to extinction.

Topes have historically been harvested for squalene, a lipid found in the liver of sharks. Although there are an abundance of plant-based and synthetic alternatives, shark liver oil remains in high demand for use in cosmetics, pharmaceuticals, dietary supplements, sunscreens, and biofuels.

Sport fishing for tope is still permitted, and trade in whole tope sharks is often allowed by direct fishing or as a by-catch product. Tops are targeted directly in fisheries, but are also particularly vulnerable to incidental capture as bycatch in pelagic gillnet and longline fisheries, as well as in trawls, hooklines, trolling lines, trammels and traps due to their preference for teleosts. fish and a tendency to swim in schools.

Accidentally captured animals become entangled in this mesh around their necks, mouths and fins, preventing proper feeding, limiting growth, causing infection or leading to extreme fatigue.

Targeted and incidental captures are more likely to occur in bays and estuaries, where pregnant females are known to seek refuge to give birth.

Habitat degradation

As top predators in the food chain, sharks are prone to accumulating high levels of toxic pollutants. Given the great sharks’ reliance on near-shore breeding grounds, toxic substances pose serious threats to the great shark throughout its range, and in California in particular, given excessive levels of DDT – an insecticide synthetic – in and around important habitats. DDT was developed in the 1940s to control diseases in military and civilian populations and to control insects in crops and livestock. [Because of health and environmental effects and its persistence in the environment, DDT’s agricultural use in the United States was banned in 1972, and a worldwide ban on its agricultural use has been in effect since 2004.]

Many marine species continue to suffer from the legacy of DDT contamination. In sharks, compounds like DDT are stored in the liver and passed from mother to offspring, leaving the offspring poisoned by DDT.

In light of research on similar species, exposure and bioaccumulation of DDT and other pollutants likely played a role in the tope shark’s decline. Studies have revealed high levels of inorganic and organic micropollutants in shark muscle and liver, including heavy metals (eg, mercury, cadmium, arsenic, lead) and various persistent organic pollutants.

Climate change and coastal development

Climate change and coastal development are particularly harmful to tope since the species depends on warm shallow areas for the rearing of pregnant young and the development of juveniles for up to two years.

Sharks are very likely to alter their distribution or expand into new habitats to follow preferable ocean conditions due to climate change. The effects of climate will cause significant changes in phytoplankton – the base of the marine food web – biomass and changes in species dominance. Phytoplankton declines will likely affect secondary and tertiary level consumers such as fish and sharks.

Rising temperatures, which primarily impact the ocean, go far beyond death, extinctions and habitat loss. Instead, rising temperatures alter fundamental processes, leading to ecological reorganization and surprises. Indeed, the loss of sharks would likely be catastrophic for marine ecosystems. Ocean changes will also increase ocean acidification, stratification and dead zones.

The need for listing as an endangered species

Current conservation regulations are ineffective in ensuring the survival of the great shark. This is exemplified by the few conservation measures present throughout the top shark’s global range, despite growing international awareness of the threats facing the species.

Listing the rod shark as an endangered species under the US Endangered Species Act and designating the species’ critical habitat in US waters would greatly improve the chances of the rod shark’s survival. species by limiting habitat destruction, reducing unsustainable harvesting and other human-caused factors, and strengthening regulatory mechanisms.

The Defend Them All Foundation and the Center for Biological Diversity hope that with this listing, the top shark population will stabilize and increase off the west coast.

Hunter Collins is a law student at the University of San Diego and an associate with the Defend Them All Foundation.

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