1. Globally, one quarter of shark and ray species are threatened with extinction due to overfishing. Effective conservation and management can facilitate population recoveries. However, these efforts depend on robust data on movement patterns and stock structure, which are lacking for many threatened species, including the Critically Endangered soupfin shark Galeorhinus galeus, a circumglobal coastalpelagic species. 2. Using passive acoustic telemetry, we continuously tracked 34 mature female soupfin sharks, surgically implanted with coded acoustic transmitters, for 7 years via 337 underwater acoustic receivers stationed along the west coast of North America. These sharks and an additional six were also externally fitted with spaghetti identification tags. Our tagging site was a shallow rocky reef off La Jolla (San Diego County), California, USA, where adult females were observed to aggregate every summer. 3. Tagged soupfin sharks were highly migratory along the west coast of North America, between Washington, USA and Baja California Sur, Mexico. However, every 3 years, they returned to waters off La Jolla, California, where they underwent gestation. This is the first conclusive evidence of triennial migration and philopatry ('homeloving') in any animal, which is apparently driven by this species' unusual triennial reproductive cycle. Females of other shark and ray species with triennial reproductive cycles are also likely to exhibit triennial cycles of migration and philopatry. 4. At least six (15%) of our tagged soupfin sharks were killed in commercial gillnets in Mexico. 2 | Journal of Applied Ecology NOSAL et AL. 1 | INTRODUC TI ON Migration, the long-distance movement between distinct habitats for distinct purposes, is widespread among animal taxa (Dingle & Drake, 2007). In long-lived, iteroparous species (i.e. most vertebrates), loop and to-and-fro migrations are most common, involving recurring round-trip journeys between breeding and nonbreeding habitats in response to seasonal changes in the environment (Ramenofsky & Wingfield, 2007). Along these migratory circuits, many animals are philopatric ('home-loving'), returning to previously occupied 'bottleneck sites' for feeding, mating, parturition, molting or staging (Mayr, 1963). Such predictable site fidelity can be used to monitor individual animals via automated tracking and markrecapture methods, to study the long-term patterns of migration within an individual's lifetime. Understanding where, when and why animals move can improve management and conservation, by identifying essential habitat, migratory corridors and bottleneck sites, and enabling more targeted management actions that are flexible in space and time (Allen & Singh, 2016). Migration and other phenological events, such as reproduction, molting and hibernation, usually cycle with a period of 1 year, regulated by endogenous circannual rhythms that are entrained to seasonally varying environmental cues such as photoperiod, temperature and rainfall (Helm et al. 2013; Visser et al. 2010). Circa...

Characterizing the behavior of coral reef fishes at home reef sites can provide insight into the mechanisms of spatial ecology and provide a framework for spatial resource management. In the Caribbean, populations of Nassau grouper Epinephelus striatus have declined due to fishing impacts on spawning aggregations. Despite local and regional efforts by fisheries managers to implement regulations protecting spawning aggregations, few Nassau grouper populations appear to be recovering. In order to improve management strategies for this critically endangered species, it is necessary to understand the spatial ecology of the species across seasons and years. In the Cayman Islands, we used a multi-year, presence/absence, depth-coded acoustic tagging dataset of Nassau grouper to characterize patterns in the species’ behavior and vertical habitat use at home reef sites. Twenty acoustically tagged individuals (56-84 cm, 70.01 ± 7.40 cm; total length, mean ± SD) maintained consistent home reef sites, although some fish regularly shifted activity centers within the home site, often following a seasonal spawning migration. Seven fish with depth-coded tags showed a higher probability of vertical movement in the hours immediately following dawn and preceding dusk. We found evidence of a positive relationship between the fish condition factor and depth of home reef site. The finding of persistent home reef sites across years suggests that properly sized spatial reserves at home reef sites can be a useful complement to spawning aggregation protection when considering management strategies for Nassau grouper.

Multispecies fisheries, particularly those that routinely adapt the timing, location, and methods of fishing to prioritize fishery targets, present a challenge to traditional single-species management approaches. Efforts to develop robust management for multispecies fisheries require an understanding of how priorities drive the network of interactions between catch of different species, especially given the added challenges presented by climate change. Using 35 years of landings data from a southern California recreational fishery, we leveraged empirical dynamic modelling methods to construct causal interaction networks among the main species targeted by the fishery. We found strong evidence for dependencies among species landings time series driven by apparent hierarchical catch preference within the fishery. In addition, by parsing the landings time series into anomalously cool, normal, and anomalously warm regimes (the last reflecting ocean temperatures anticipated by 2040), we found that network complexity was highest during warm periods. Our findings suggest that as ocean temperatures continue to rise, so too will the risk of unintended consequences from single species management in this multispecies fishery.