Advances in understanding the roles and benefits of nursery areas for elasmobranch populations

Abstract

Nursery areas are critical to the survival of many marine species, and it is widely accepted that elasmobranch species use nursery areas where they improve species fitness. A 2007 review proposed an approach to identify elasmobranch nursery areas to help clarify their location and use. Here we examine progress towards defining elasmobranch nurseries in the intervening ≥10 years. Many studies have used these criteria, and some have tested their effectiveness, but it is apparent that there is still much to learn. Our current understanding of elasmobranch nurseries is biased towards tropical coastal shark species with few studies of temperate, pelagic, deep-water or batoid species. Recent research has used the criteria to more accurately identify nursery areas, determine that some species may not use them and, at times, improve conservation and management. Results are also revealing that some areas considered to be nurseries do not meet the criteria. Although we have learned a great deal about the location and use of elasmobranch nurseries, there are still several questions to be answered and species to be considered. Continued application of nursery criteria and improved knowledge of nursery areas will lead to improved conservation and management systems.

Updated reproductive parameters for the shortfin mako (Isurus oxyrinchus) in the North Atlantic Ocean with inferences of distribution by sex and reproductive stage

“…Although the distribution data used in this study were spatially and temporally dependent on fishing effort, the same is true for the majority of data used in other studies to describe the distributions of pelagic sharks (Mucientes et al, 2009;Heupel et al, 2018). Some gear configuration changes (Federal Register, 2004;Coelho and Muñoz-Lechuga, 2019) may have influenced the catchability of sharks over time (Reinhardt et al, 2018), but no management or systematic changes in the distribution of fishing effort would have affected the geographic range of the catch data used.…”

“…The identification of pupping and nursery areas for sharks is crucial to protect vulnerable life stages and support conservation goals (Heupel et al, 2007;Kinney and Simpfendorfer, 2009;Heupel et al, 2018). Unless movement following birth is substantial, the distribution of the youngest age classes should delineate potential birthing and nursery areas.…”

Habitat Use Patterns and Identification of Essential Habitat for an Endangered Coastal Shark With Vertebrae Microchemistry: The Case Study of Carcharhinus porosus

“…Since these trace element concentrations are marked in the vertebrae and no evidence of element reabsorption by the body exists, evaluating their variations in hard parts enables the understanding of changes in trace element composition throughout an individual's lifetime. With these, key information on the type of habitat a species uses during each life stage (McMillan et al, 2017), and even potential nursery areas (Tillett et al, 2011;Lewis et al, 2016;Smith et al, 2016;Heupel et al, 2018) can be obtained. However, several aspects of this methodology need to be addressed to improve the robustness of conclusions, especially in areas with little environmental variation such as the BNC.…”

Size frequency, dispersal distances and variable growth rates of young sharks in a multi‐species aggregation

“…High abundances of neonatal and young sharks does not alone classify a habitat as a shark nursery; to meet the criteria of a shark nursery, long‐term site attachment as well as a repetitive use across years need to be prevalent (Heupel et al , ). Although this approach helps define shark nurseries for management and conservation decisions (Heupel et al , , ), the functional importance of these coastal habitats for young sharks remains contentious. Recent work suggests that shallow, nearshore nurseries may not be as protective and resource abundant as previously thought (Branstetter, ), because high pup mortality, weight loss and slow growth rates are found in monospecific shark nurseries (Duncan & Holland, ; Heupel & Simpfendorfer, ; Lowe, ).…”