Posted By
ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000
Email: info@coralcoe.org.au
Nearly a third of all elasmobranch species—sharks, rays, and skates—face extinction. Without proper management and conservation efforts climate change is likely to make things worse for them, now and into the future.
In our recent review, we discuss a suite of direct and indirect stressors on elasmobranch reproduction, growth, and development, as these key life phases are crucial to maintain and rebuild populations.
Direct stressors include fisheries interactions, poor coastal management, and runoff/pollution. Indirect stressors include climate change impacts—mainly ocean warming and acidification.
Broadly, we found that all of these stressors have varying negative effects on reproduction and development.
Sharks, rays and skates are slow growing, have a late age of maturity, and produce very few offspring in comparison to bony fishes. It’s these factors that make the elasmobranch species extremely susceptible to population declines, as they cannot reproduce quickly.
Currently, targeted fisheries and by-catch interactions—individuals that are caught accidentally when targeting another species—are the main threat to elasmobranchs globally.
Capture often results in incidental abortion, and post-release stress can disrupt reproduction long after the capture event has concluded. Poor coastal management can decrease areas that were once suitable nursery habitats and crucial for early development in both live-bearing and egg-laying elasmobranchs. Heavy metals and pesticides from runoff transfer to the offspring during development; though the specific effects of these chemicals on survival are still unknown.
Fig 1. Sharks, rays and skates are subject to a number of combined human impacts
Climate change will indirectly effect elasmobranch reproduction and development via increasing ocean temperatures and acidity. These changes can affect physiological processes and behaviours necessary for essential tasks such as foraging, movement, growth—ultimately, survival.
However, climate change stressors are not occurring in isolation, and more research is needed to assess combined stressors. For example, what happens when coastal nursery habitats are jeopardised and face increased water temperatures?
Although we often imagine elasmobranchs as large, free-roaming, tough ocean predators, approximately 40 percent of elasmobranch species spend most of their time on the bottom of the ocean and produce relatively small offspring that hatch from eggs.
In our review, we also performed a case study to examine the relationship between temperature and incubation time of 28 different egg-laying elasmobranch species. The data we collected are useful in predicting habitat suitability and elasmobranch development over the coming century.
Our review not only provides a comprehensive synthesis of the few examples we do have for these stressors, but it also highlights the many areas of research that are crucial moving forward to conserve and protect elasmobranchs—particularly in relation to climate change.
PAPER
Wheeler C, Gervais C, Johnson M, Vance S, Rui R, Mandelman J, Rummer J. (2020). ‘Anthropogenic stressors influence reproduction and development in elasmobranch fishes’. Reviews in Fish Biology and Fisheries. DOI: 10.1007/s11160-020-09604-0.
The most extensive reef survey of the Coral Sea Marine Park ever undertaken will continue this week as scientists from ARC Centre of Excellence for Coral Reef Studies at James Cook University (Coral C
Scientists have used modern genetic techniques to prove age-old assumptions about what sizes of fish to leave in the sea to preserve the future of local fisheries. “We’ve known for decades that
Scientists say outdated assumptions around gender continue to hinder effective and fair policymaking and action for climate mitigation and adaptation. Lead author of a new study, Dr Jacqueline Lau
For the first time, scientists have assessed how many corals there are in the Pacific Ocean—and evaluated their risk of extinction. While the answer to “how many coral species are there?” is
Abstract: When a coral reef is bleached, a temperate kelp forest is destroyed by an army of sea urchins, or when intense fishing pressure is removed through the establishment of a marine park, the ma
Abstract: The fate of fish larvae during the pelagic phase has profound effects on replenishment of marine populations that are critical for human and ecosystem health. The survival and transport of l
Abstract: Neonate sharks experience high predation during early ontogeny. For this reason, predator avoidance is the major driver of shallow-water habitat use in neonate sharks. When a predator encoun
Abstract: Humans have been harvesting predators and other creatures from the global oceans for millennia. More recently, conservation measures, such as marine reserves, have been established to restor
Abstract: The Great Barrier Reef World Heritage Area (WHA) is one of the most precious and diverse ecosystems on Earth. It is highly valued by people within Australia and worldwide and is critical to
Abstract: We frequently hear about demise and decline in fisheries systems. This narrative can inadvertently shift thefocus of research and funding away from the opportunities and benefits avail
Abstract: Multiple habitats in a tropical seascape are increasingly recognized as interconnected to one another. Mangroves, seagrass beds, and macroaglal beds are important components of a tropical se
Abstract: Current conservation goals for reef-building corals under climate change involve boosting desirable traits like heat tolerance and fast growth in natural and restored coral populations. This
ARC Centre of Excellence for Coral Reef Studies
James Cook University Townsville
Queensland 4811 Australia
Phone: 61 7 4781 4000
Email: info@coralcoe.org.au