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The North Atlantic Designatable Unit (DU) of Shortfin Mako Shark was assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as Endangered in April 2019, and is currently under consideration for listing under Schedule 1 of the Species at Risk Act (SARA). The Recovery Potential Assessment (RPA) presented here provides information to support the listing recommendation and any recovery actions, should the species be listed. Shortfin Mako occurs throughout the Northern Hemisphere of the Atlantic Ocean. The biological characteristics of Shortfin Mako (i.e., relatively long lifespan, late maturity, and low reproductive output) make the population very susceptible to fishing pressure, which is the main threat identified in the North Atlantic. Multiple international and Canadian fisheries intercept Shortfin Mako as bycatch, and the most recent assessment of the DU predicts that it is overfished relative to biomass at Maximum Sustainable Yield (MSY). Reducing total removals in the North Atlantic to 500 mt is projected to have a > 50% probability of population recovery by 2070. For comparison, international and Canadian removals in 2019 totalled 1,863 mt and 63 mt, respectively. Considering just Canadian fleets, interception probabilities are highest from pelagic longline, with an average of 48% of observed sets encountering Shortfin Mako, followed by bottom longline (0.4% of sets) and otter trawl (0.2% of sets). The most effective Canadian mitigation measure for Shortfin Mako will be the new landings prohibition, implemented in 2020 for pelagic longline and scheduled for implementation in 2021 for fixed-gear groundfish fisheries. The effectiveness of other mitigation measures are relatively unclear and, in many cases, would require dedicated experimentation to test. The current requirement to use circle hooks may need to be revised due to new evidence that increased catchability outweighs any reduction in post-release mortality for Shortfin Mako, thus leading to greater total mortality as compared to using J-hooks. Given the current level of international fisheries removals and the extent of mitigation already in place in Canada, there is very little scope for mitigation actions by Canada to measurably affect recovery potential. [ABSTRACT FROM AUTHOR]

Describing how population-level survival rates are influenced by environmental change becomes necessary during recovery planning to identify threats that should be the focus for future remediation efforts. However, the ways in which data are analyzed have the potential to change our ecological understanding and thus subsequent recommendations for remedial actions to address threats. In regression, distributional assumptions underlying short time series of survival estimates cannot be investigated a priori and data likely contain points that do not follow the general trend (outliers) as well as contain additional variation relative to an assumed distribution (overdispersion). Using juvenile survival data from three endangered Atlantic salmon Salmo salar L. populations in response to hydrological variation, four distributions for the response were compared using lognormal and generalized linear models ( GLM). The influence of outliers as well as overdispersion was investigated by comparing conclusions from robust regressions with these lognormal models and GLMs. The analyses strongly supported the use of a lognormal distribution for survival estimates (i.e., modeling the instantaneous rate of mortality as the response) and would have led to ambiguity in the identification of significant hydrological predictors as well as low overall confidence in the predicted relationships if only GLMs had been considered. However, using robust regression to evaluate the effect of additional variation and outliers in the data relative to regression assumptions resulted in a better understanding of relationships between hydrological variables and survival that could be used for population-specific recovery planning. This manuscript highlights how a systematic analysis that explicitly considers what monitoring data represent and where variation is likely to come from is required in order to draw meaningful conclusions when analyzing changes in survival relative to environmental variation to aid in recovery planning. [ABSTRACT FROM AUTHOR]

The eastern Cape Breton (ECB) designable unit (DU) of Atlantic SalmonSalmo salarcomprises populations in 46 or more rivers in the eastern portion of Cape Breton Island, Nova Scotia, Canada. In 2010, the Committee on the Status of Endangered Wildlife in Canada classified the ECB DU as endangered. In support of recovery planning processes, we developed an integrated, statistical, life history-based model for evaluating the dynamics of populations belonging to this DU. Using maximum likelihood, the model was fitted to recreational fishery catch and effort data, fish counts by divers, intermittent mark–recapture data, and sparse age composition data for two populations in the DU. The model output included estimates of maximum lifetime reproductive rate () and equilibrium population size—parameters that are important for determining extinction risk. Thefor the Middle River population (2.82 spawners/spawner) was double that of the Baddeck River population (1.39 spawners/spawner). Thesevalues would be considered low for Atlantic Salmon populations in general but are higher than those of populations in a neighboring endangered DU to the south. Slightly negative trends in recruitment deviates may indicate declining productivity in the two ECB populations; based on equilibrium analyses, neither population is expected to achieve the proposed recovery targets without an increase in productivity, survival, or both. Atlantic Salmon populations and habitat characteristics in ECB exhibit considerable diversity. Therefore, the dynamics of the Middle River and Baddeck River populations are unlikely to be representative of all populations in the ECB DU. Based on recent trends in recreational fishery catches, these two populations are likely among the healthier populations within the DU. Received July 8, 2014; accepted December 17, 2014 [ABSTRACT FROM AUTHOR]

The article discusses the life-history-based population viability analysis that explicitly incorporates declines in fitness attributable to captive breeding and rearing using the breeder's equation as part of the projection model. The study was conducted in endangered inner Bay of Fundy Atlantic Salmon. It concludes that the useful duration of supplementation programs may be limited to short-term population increase and may not be a workable strategy for longer term recovery planning.