Science Advisory Report 2018/051

Conservation benefits to assisting live-stranded neonates or entrapped juvenile beluga (Delpinapterus leucas) from the St. Lawrence River Estuary

Summary

• There are periodic reports (i.e., one or two reports every two to three years) of a live-stranded neonate (days to weeks old) SLE beluga, or of an independent (weaned) juvenile entrapped in semi-enclosed areas that cannot return to their normal habitat unassisted.
• Beluga neonates that are found stranded alive have been separated from their mother. Calves feed exclusively on milk during the first year, so if left alone, neonates will die.
• The health of neonates deteriorates rapidly when stranded relative to healthy conspecifics of the same age. Therefore, the chances of survival if relocated are likely to be low.
• For a live-stranded neonate to survive, nursing must resume quickly (i.e., within several hours) after relocation. Therefore, there needs to be a female willing to care for the calf. The likelihood of such an event occurring within this time frame is unknown but, based upon existing literature, is most probably close to nil.
• The chances of survival of entrapped juvenile beluga are better than for neonates given their ability to feed independently.
• The benefits of assisting live-stranded or entrapped juvenile beluga were examined from the perspective of their contribution to population recovery to determine if they meet the objective of Conservation Translocation, which requires that such actions result in a measurable conservation benefit at the population level.
• The age-frequency distribution of dead animals found in the St. Lawrence Estuary, from the years 1983-2017 was used to construct a population model. Different model scenarios were examined in attempts to replicate a period of stability in the population (1983-2000) and a period of population decline (2001-2012).
• Model results showed that improvements in survival made a greater contribution to population trend than did changes in reproduction. They also indicated that calves are much more likely to die than juveniles and adults, and that the greatest increase in population growth rate is achieved by improving survival among juveniles and young adults. There are uncertainties in some of the model parameters or assumptions but they are unlikely to affect these general model conclusions.
• The model indicated that, assuming survival of an entrapped and released juvenile is similar to that of conspecifics, 10 juveniles would need to be relocated each year to halt the decline. For neonates, up to 19 individuals per year would need to be reintroduced and adopted successfully to halt the decline.
• Reports of live-stranded neonates or entrapped juveniles are infrequent and the probability of survival of relocated neonates is close to nil. Therefore, the benefit of relocating these few individuals to population recovery is nil and does not meet the objectives of Conservation Translocation.
• Although the occurrences of entrapped juveniles are rare, there is a higher likelihood that these individuals can survive following relocation. While from a conservation perspective the benefit of relocating entrapped juveniles to the population as a whole is likely nil given the rarity of these events, relocating these individuals may be considered on other grounds. Some of the factors that need to be considered have been identified previously (e.g. DFO Release and Rehabilitation Criteria).
• From an animal welfare perspective, relocating neonates or letting nature take its course might result in increased distress and suffering, and ultimately mortality. Under these situations, euthanasia should be considered. In this case, a necropsy would improve our understanding of potential causes for stranding. An alternative consideration would be to take live-stranded neonates into captivity. However, neonates are not considered suitable for future release under the proposed DFO guidelines for the release of rehabilitated marine mammals.

This Science Advisory Report is from the 26 February – 2 March 2018 St. Lawrence Estuary live beluga calf strandings. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Complete document (PDF, 650 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.