GOA Noteworthy (formerly Hot Topics) 2019

Noteworthy (formerly Hot Topics)(pdf)

This section replaces the previously-named Hot Topics. We include information here that is deemed of relevance to ecosystem considerations of fisheries managers, but does not fit our typical indicator format. Information included here is often new, a one-time event, qualitative, or some other type of non-standard ecosystem indicator.

Fall 2018-2019 marine heatwave

As of 1 November 2019, the western Gulf of Alaska shelf area largely remained in marine heatwave conditions from late September 2018 through mid-October 2019 (Figure 3). This implies that for most of the 2018/2019 winter and to an even greater extent during summer 2019 (Figure 4), temperatures have remained above the 90% threshold as defined by Hobday et al. (2016). While overall cumulative intensities (°C days) were similar for 2015 and 2019, a greater proportion of the heatwave took place during summer in 2019 relative to 2015. Summer 2019 temperatures were higher than those of 2016, but the anomalies were higher in 2016 because the highest temperatures were on days which are not on average the warmest days (Figure 5). The current heatwave dropped below the threshold on 12 October 2019 likely due to strong storms in early October that enhanced surface mixing. However, the threshold was exceeded again on 4 November. Also, SST forecast models are predicting the continuation of warmer than normal temperatures in the NE Pacific (see p.41). Together, these suggest that heatwave conditions may persist through the winter 2019/2020. Full impacts of this heatwave to the ecosystem are currently unknown, but will likely depend on whether it continues and if so, its extent and duration.

Methods The daily sea surface temperatures for 1981 through October 2019 were retrieved from the NOAA High-resolution Blended Analysis Data database (NOAA 2017) and filtered to include only data from the central Gulf of Alaska between 145oW and 160oW longitude for waters less than 300m in depth. The overall daily mean sea surface temperature was then calculated for the entire region. These daily mean sea surface temperatures data were processed through the R package heatwaveR (Schlegel and Smit 2018) to obtain the marine heatwave cumulative intensity (MHWCI)(Hobday et al., 2016) value where we defined a heatwave as 5 days or more with daily mean sea surface temperatures greater than the 90th percentile of the 1 January 1983 through 31 December 2012 time series for the dates involved. The MHWCI were then summed for each year to create an annual index of MHWCI and summed for each year for the months of January through March, November, and December to create an annual winter index of MHWCI.

Contributed by Steve Barbeaux and Stephani Zador

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Figure 3: Gulf of Alaska temperatures with heatwave threshold (red line) as defined by Hobday et al. (2016). Temperatures are standardized to remove season signals. Time series updated 5 November 2019.

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Figure 4: Index of the sum of the annual marine heatwave cumulative intensity (oC days) for 1981-2019 (larger red points) and index of the sum of the annual winter marine heatwave cumulative intensity for 1981-2019 (smaller blue points) from the daily mean sea surface temperatures NOAA high resolution blended analysis data for the Central Gulf of Alaska. The 2019 index value is the sum through 5 November 2019.

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Figure 5: Gulf of Alaska temperatures with heatwave thresholds as defined by Hobday et al. (2016). Time series updated 1 November 2019.

Unusual Mortality Event: Gray Whales

Since January of 2019, elevated numbers of eastern North Pacific gray whale (Eschrichtius robustus) mortalities have occurred along the west coast of North America, stretching from Mexico to Alaska. In May of 2019, the increased strandings were declared an Unusual Mortality Event (UME) (Table 1, Figure 6).

Table 1: Total number of gray whale strandings by location from January 1-October 30, 2019.

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Gray whale life history includes an annual round-trip migration of up to 20,000 km. The mortalities started off the western coast of the southern Baja California Peninsula where gray whales over-winter to mate and calve. Mortalities followed the late winter/spring migration up to Alaskan waters where foraging occurs before the fasting return journey south. The first Alaskan gray whale stranding occurred on May 9th in Turnagain Arm of Cook Inlet. Mortalities have continued throughout the summer with hotspots around Kodiak Island, Bristol Bay, and coastal waters of the Bering Strait and Chukchi Sea (Figure 7).

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Figure 6: Number of gray whale strandings in Alaska by year, 2001-2019 (2019 numbers through October). As part of the UME investigation process, NOAA has assembled an independent team of scientists to coordinate with the Working Group on Marine Mammal Unusual Mortality Events to review the data collected, sample stranded whales, and determine the next steps for the investigation. Full or partial necropsy examinations were conducted on a subset of the whales. Preliminary findings from several of the whales have shown evidence of emaciation; however, these findings are not consistent across all of the whales examined. Furthermore, while benthic prey (primarily ampelecid amphipods) in the Bering, Chukchi, and Beaufort Seas are considered the mainstay of gray whale foraging, there is also significant variability in foraging behavior along the west coast depending on the location, season, year, and subset of whales (Moore et al., 2007; Calambokidis, 2013).

The eastern North Pacific gray whale is considered something of an "ecosystem sentinel" for the North Pacific and western arctic ecosystems. Correlations between changes in the distribution and behavior of gray whales and environmental change in these regions indicates the species may be effective sentinels (Moore, 2008).

A gray whale UME also occurred along the West Coast from Mexico to Alaska in 1999/2000. Although no definite conclusion was reached, the most likely precipitating factor was considered malnutrition, possibly associated with a decrease in the quantity and quality of prey items or the numbers of gray whales overwhelming the prey base as the population reached carrying capacity.

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Figure 7: Locations of gray whale strandings in Alaska (NOAA/NMFS Alaska Region Marine Mammal Stranding Network unpublished data).

Contributed by Kate Savage, DVM Protected Resources Division NOAA Fisheries

Market Squid Spawning in Southeast Alaska

Market squid (Doryteuthis opalescens) are a small Myopsid squid (Figure 8) that typically inhabits nearshore waters along the Pacific coast of North America. They are an important commercial species, particularly in fisheries along the coast of California (Perretti et al., 2015) as well as an important prey species for many predators, including various fish, marine mammal, and seabirds. Although this species occurs from Baja California to southeast Alaska, it is most abundant from Baja to central California. Market squid historically spawn from Baja California to southern British Columbia. Water temperatures farther north were presumably too cold for spawning in the past.

Over the years, small numbers of market squid have been sporadically observed at Little Port Walter (Figure 8), a small fjord located on southern Baranof Island in southeast Alaska. Biologists at the Little Port Walter research station have been monitoring marine life and ocean conditions at the site since the 1930s. A notable

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Figure 8: Map of Little Port Walter in southeast Alaska

change occurred in 2015 when hundreds of market squid were observed at the station. In addition to the increased number of individuals present, the squid were also spawning and laying eggs on mesh netting being used at the site (Figure 9). Sizable schools of market squid and subsequent spawning events occurred in 2016, 2018, and 2019. No squid were seen in the area during 2017.

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Figure 9: Market squid observed at the Little Port Walter research station (left panel) and market squid egg cases laid on netting at the station (right panel).

Contributed by John H. Eiler and Alexa L. Marinelli

Local Environmental (LEO) Network

The NMFS AFSC is interested in documenting and learning from citizen science observations that may be incorporated into Ecosystem Status Reports (ESRs). The 2017 ESR identified the LEO Network as a potential platform for tracking these observations, and the authors were encouraged by the Council and SSC to continue exploring the utilization of this framework in future reports. Other citizen science efforts exist in Alaska, but to our knowledge these efforts are mostly project specific (e.g., bird spotting and identification) or community specific and do not provide sufficient breadth to cover the myriad of anomalous environmental observations relevant to the Council. While the LEO Network also suffers from this issue, it still appears to be the citizen science database with the most coverage across species and regions of the state.

The LEO Network was launched in 2012 by the Alaska Native Tribal Health Consortium (ANTHC) as a tool for local observers in the Arctic to share information about climate and other drivers of environmental change (see: https://www.leonetwork.org/en/docs/about/about). Anyone may join the network and provide observations, and the network now spans the globe. Consultants with relevant expertise often, but not always, review the observations and provide feedback. The observations are of unusual environmental events or notable environmental changes, reported by geographic location and date, and classified by relevant category (or multiple relevant categories) such as weather, land, fish, sea mammals, ocean/sea, etc.

Figure 10 shows the number of LEO Network observations from August 2, 2018 to August 14, 2019 in the Gulf of Alaska (GOA) with the frequency by category (dates were specified to include observations that were part of the ESR in 2018). These categories are based on analysis of the 110 total observations in 2018 and 2019 in the GOA and are not limited to the marine environment. The observations in Figure 11 were made in 30 total communities. Observations in 2018 were dominated by unusually large numbers of bear sightings and human interactions across Gulf of Alaska communities, which observers attributed to small salmon runs causing bears to change their behavior in search of food. In 2019, the observations were dominated by references to extreme weather events, especially the hot and dry summer across Southeast and Southcentral Alaska coupled with excessive haze from large wild.res in the Interior.

In response to the Council's and SSC's previous comments on the use of LEO Network observations in this report, AFSC is currently developing a LEO Network project to solicit observations from community members on specific ecological questions. Alaska State agencies, non-pro.t organizations, universities, and U.S. federal agencies have similarly developed projects on the network to track observations specific to their area of interest, e.g., weather events, .sh pathology, subsistence harvests, etc. AFSC is also actively pursuing opportunities to examine ways of incorporating local and traditional knowledge into fisheries management in the North Pacific with the Council's Bering Sea Fishery Ecosystem Plan and Social Science Planning Team and through targeted research efforts.

Contributed by Marysia Szymkowiak

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Figure 10: Leo Nerwork Observation location for Alaska for 2018 and 2019 (August to August) source:

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Figure 11: Numbers of LEA Network Observations in GOA communities, August 2018 through August 2019.