Review of St. Anns Bank Marine Protected Area monitoring

St. Anns Bank Marine Protected Area (MPA) was designated under Canada’s Oceans Act in 2017. A data review was conducted to examine baseline data and ongoing survey data contributions towards monitoring the MPA’s conservation objectives. Long-term data sources reviewed include the Atlantic Zone Monitoring Program’s (AZMP) oceanographic and biological data, passive acoustic monitoring for cetaceans, acoustic telemetry to examine fish movement and diversity in and around the MPA, and the Maritimes Region’s Snow Crab Survey. St. Anns Bank is situated in the outflow of the Gulf of St. Lawrence and shows similar year to-year variability in oceanographic conditions when compared to areas upstream and downstream as measured on the inshore stations of the AZMP’s Cabot Strait and Louisbourg monitoring lines, respectively. Annual satellite sea surface temperatures across the MPA have increased since 2012. St. Anns Bank water column temperatures from near surface to bottom recorded during the fall have also increased since 2012, with most record highs observed post-2020, which is consistent with areas upstream and downstream. St. Anns Bank showed high variability in in situ chlorophyll-a and nutrient concentrations, which for surface conditions is partially related to the timing of sampling relative to the phytoplankton spring bloom. A statistically significant increasing trend has been observed in surface satellite chlorophyll-a concentrations time series, with above-normal anomalies occurring in the fall in recent years. Since 2012, emerging trends in biogeochemical properties in St. Anns Bank (e.g., decreasing zooplankton size structure, mostly at- or lower-than-normal Calanus finmarchicus abundance, although returning to above-normal abundances of C. finmarchicus in 2023) appears to be related to the shift to a warmer-water environment. The 3-year carbonate chemistry dataset suggests that the bottom waters of St. Anns Bank are susceptible to ocean acidification and should continue to be monitored. Comparative analysis of the physical, chemical, and lower-trophic level biological conditions in St. Anns Bank in relation to the inshore stations on core AZMP lines, Cabot Strait and Louisbourg, revealed spatial and temporal similarities among these areas. Given limited resources for direct environmental monitoring, it is feasible to infer environmental conditions in St. Anns Bank from data collected by satellite observations and nearby stations. However, to maintain a comprehensive understanding and ensure accurate monitoring of the MPA, continued AZMP monitoring of St. Anns Bank is advised. Catch and diet data were analyzed from the annual Maritimes Snow Crab Survey between 2015, when dedicated MPA stations were added, and 2023. Species richness of fishes and invertebrates based on catch data is comparable inside and immediately outside the MPA and appears to be stable over this time period. Diet data collected from fish stomachs by the survey increased the species richness captured in the MPA compared to the trawl catch alone. Diet composition largely overlaps in individuals of a given species captured inside versus outside the MPA, and appears relatively stable over time. From 2015 to 2023 the size structure for most fish species remained stable, with the exception of Atlantic Wolffish and Snow Crab, which both exhibited an increase in average size. These size increases corresponded with a rise in the biomass for each species. Although the abundance of Atlantic Wolffish and Snow Crab remained relatively stable, the increase in biomass implies a shift in the overall size structure at the survey stations. The Maritimes Snow Crab Survey using current dedicated stations appears adequate for detecting changes in fish and invertebrate species richness and abundance in the MPA. A more comprehensive examination of the MPA’s biodiversity and abundance of American Plaice and Snow Crab in particular would require additional survey effort. To reliably detect small changes in abundance inside and immediately outside the MPA using this survey would require either doubling the number of stations, as informed by the power analyses. Complementary, alternative, and non-invasive monitoring methods may also provide data to detect changes in abundance. A diverse assemblage of 19 cetacean species was detected through a combination of passive acoustic monitoring and opportunistic sightings in and around (within 50 nautical miles) St. Anns Bank MPA. Between 2015 and 2023, passive acoustic monitoring of six baleen whale species from five stations in the MPA revealed spatial and seasonal variability in occurrence. Blue, Fin, Sei, and Humpback Whales were detected year-round, while Minke and North Atlantic Right Whales were more sporadic and seasonal. Blue and Fin Whales occurred more commonly at deeper stations and call presence peaked in fall and winter. Humpback Whales occurred more commonly at on-shelf stations and call presence peaked in spring, and again in fall and winter. Sei Whales occurred at all stations and call presence peaked in summer. North Atlantic Right and Minke Whale calls occasionally occurred at almost all stations, mainly in fall. Relatively consistent acoustic presence at on-shelf stations suggests regular use of these areas by some species (e.g., Humpback Whales). Seasonal patterns in acoustic occurrence at deeper stations is likely linked to the broader scale movements of some species (e.g., Blue and Fin Whales) into and out of the Gulf of St. Lawrence. Continuing passive acoustic monitoring will enable assessment of year-round presence of cetacean species, particularly baleen whales, in selected areas of the MPA. This method offers near-continuous and seasonal information on species occurrence. To support assessment of long-term trends in cetacean occurrence, future monitoring recommendations involve establishing consistent passive acoustic monitoring stations over time in both deeper and on-shelf waters of the MPA. The St. Anns Bank MPA tagging program (2015–2023) has provided information on the residency and movement of Atlantic Cod, Atlantic Halibut, and Atlantic Striped Wolffish within and through the MPA. Simultaneously, 33 other tagging projects have contributed to the monitoring of 13 species, including the following species that have sufficient data to examine long-term trends in species seasonal residency within and movement through the MPA: Atlantic Salmon, Bluefin Tuna, Blue Shark, Atlantic Cod, and White Shark. Tagged species detected include species resident in the MPA for most of the year (Atlantic Cod, Atlantic Halibut, Atlantic Wolffish), occurrence throughout summer-fall (Pelagic sharks, Bluefin Tuna), and short-term annual summer occurrence (Atlantic Salmon). Scatarie Bank was identified as a residency hotspot for the majority of species that have sufficient data to examine spatial trends, with the exception of Atlantic Salmon detected primarily in the east. To improve assessment of species' directional movement and spatial and temporal use of the MPA as it relates to the conservation objectives, the current acoustic telemetry array and tagging program should be re-evaluated and redesigned. The meeting independently reviewed long-term data sources. Future analysis can integrate these data for a more comprehensive understanding of the MPA that may reveal connections between the AZMP’s oceanographic and biological data, cetacean monitoring through passive acoustics, fish movement and diversity using acoustic telemetry in and around the MPA, and the Maritimes Snow Crab Survey. Additionally, potential new long term data sources may be explored to align with the MPA objectives. The utility and expectations of data streams within the MPA with a focus on their long-term reliability for effective monitoring, including their ability to evaluate trends over time, were reviewed with the intention of establishing realistic expectations for sustainable monitoring not only within the MPA but also across other conservation sites. This was an opportunity to reconcile the long-term data streams of current monitoring efforts with previous advice on indicators, thereby aligning the reliability of long-term data streams with the MPA's conservation objectives. Meeting participants recommended partnering with Rightsholders and Indigenous organizations to conduct monitoring initiatives in accordance with the vision outlined in the St. Anns Bank Marine Protected Area Management Plan.

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