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SCIENTIFIC COMMITTEE �AD HOC WORKING GROUP ON NARWHAL IN EAST GREENLAND

Roderick Hobbs

Chair of the NEGWG

NAMMCO Annual Meeting 28

22–25 March 2021

NAMMCO Annual Meeting 28

22–25 March 2021

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Distribution & Stock Structure

^{Three proposed management areas for narwhals in East Greenland.}

¹⁾ ^{Ittoqqortoormiit & Scoresby Sound}

^{2) Kangerlussuaq}

^{3) Tasiilaq}

^{Blue line indicates the} ^{previous segregation of two management areas.}

^{Blue dots represent settlements, with Tasiilaq and Ittoqqortoormiit superimposed.}

NAMMCO Annual Meeting 28

22–25 March 2021

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Distribution & Stock Structure

Tracks of two narwhals tagged in Hjørnedal near hunting grounds in late summer. These narwhal moved out of the fjord system in early November and stayed in offshore areas south of Scoresby Sound through winter and spring until mid June when their transmitters stopped.

Ittoqqortoormiit

NAMMCO Annual Meeting 28

22–25 March 2021

There is some uncertainty regarding stock structure in Management Area 1 (Ittoqqortoormiit /Scoresby Sound). Specifically, whether this area is inhabited by two populations at different times of the year. This possibility is indicated by the seasonal distribution of catches as well as tracking data. Narwhals tagged in Hjørnedal near hunting grounds in summer moved out of the fjord system in fall and stayed in offshore areas south of Scoresby Sound through winter and spring. This map shows two tracks and as you can see, both whales moved out of Scoresby Sound in early November and neither had returned by mid June when their transmissions ceased. During April-June catches are reported at the ice edge outside Ittoqqortoormiit while these tagged whales were offshore. This suggests two possibilities: 1) there is a second population in Scoresby Sound that does not enter the tagging area during summer and remains in the northern Sound during spring, or 2) there is migration down from a population in the north (e.g. Dove Bay). There is currently no evidence to support either of these over the other and further work is required to resolve stock structure in this area.

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2016 Aerial Survey Scoresby Sound to Tasiilaq

^{The survey was conducted during 17 to 25 August 2016 covering the fjord system of Scoresby Sound, a sample of the fjords along the Blosseville Coast, the Kangerlussuaq fjord, the fjords south of 65°N and some coastal areas (black lines).}

^{Red dots indicate locations of narwhal sightings.}

NAMMCO Annual Meeting 28

22–25 March 2021

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2017 Survey of Scoresby Sound

^{Black lines are survey tracklines.}

^{Red dots indicate locations of}

^{narwhal sightings.}

NAMMCO Annual Meeting 28

22–25 March 2021

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Abundance Estimated for Each Management Area (%CV)

Year	Scoresby Sound only	Area 1 Ittoqqortoormiit Scoresby Sound & south to 68°30’N	Area 2 Kangerlussuaq & 68°30’N to 67°N	Area 3 Tasiilaq & south of 67°N
1983	1180 (34)
1984	401 (58)
2008		1940 (57)	613 (71)	206 (55)
2016		433 (49)	269 (37)	***
2017	246 (43)

NAMMCO Annual Meeting 28

22–25 March 2021

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Total Removals by Year for Each Management Area 2010-2019

Year	Total Catch in Area 1	Total Catch in Areas 2 & 3	Catch in Area 2	Catch in Area 3	Total Removals Area 1	Total Removals Area 2	Total Removals Area 3
2010	16	25			25	16	14
2011	30	15	14	1	37	17	1
2012	31	17	2	14	39	2	17
2013	47	19	2	14	59	2	17
2014	63	18	11	2	82	13	2
2015	74	20	11	2	82	13	2
2016	38	15	0	14	50	0	17
2017	60	33	21	3	74	25	4
2018	51	23	15	3	67	18	4
2019	50	17	3	10	61	4	12
Average	46	20.2	7.9	6.6	58.4	11.2	9.4

NAMMCO Annual Meeting 28

22–25 March 2021

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Pregnancy Rate in Area 1

NAMMCO Annual Meeting 28

22–25 March 2021

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Habitat Changes & Population Responses

Major oceanographic changes have occurred in Southeast Greenland

Lack of pack ice in the summer.
Increasing sea temperatures.

Resulting effects in the marine ecosystem include:

Changes in fish fauna and distribution.
Arrival of large numbers of boreal cetaceans either new to the area or in much larger numbers (e.g. humpback, fin, killer, and pilot whales as well as white- beaked dolphins).

Narwhals are dependent on cold water and have limited ability to dissipate heat and thus can not easily adapt to these warming temperatures.
Changes in fish fauna mean that narwhal's preferred prey may be displaced.
Arrival of new cetacean species means increased competition for prey, predation by killer whales, and exposure to novel diseases and parasites.
Recently narwhals have been seen in areas north of their traditional range (e.g. Dove Bay), suggesting that new narwhal habitat is becoming available to the north as habitat is lost in Southeast Greenland.

NAMMCO Annual Meeting 28

22–25 March 2021

Two major oceanographic changes have been observed in coastal areas of Southeast Greenland - a lack of pack ice in summer and increasing sea temperatures. This has had cascading effects on the marine ecosystem, including changing fish fauna and the presence of a large number of boreal cetaceans either new to the area or now occurring in surprisingly large numbers (e.g. humpback, fin, killer, and pilot whales as well as white- beaked dolphins). This leads to loss of preferred prey, competition, predation and exposure to novel pathogens and parasites.

Narwhals are endemic to the Arctic and depend on cold water. Their habitat range is therefore being restricted by the warming oceans. Since they primarily get rid of heat through the dorsal ridge and tail fluke, their ability to adapt to these warming temperatures is also limited. There have recently been several sightings of narwhals in areas north of their traditional range (e.g. Dove Bay), suggesting that new narwhal habitat is becoming available to the north as habitat is lost in Southeast Greenland. While evidence suggests that a combination of hunting and climate change is negatively impacting the long-term viability of narwhal populations in Southeast Greenland further research is needed before we can include these impacts in the assessment models.

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Population Models for the Assessment

NAMMCO Annual Meeting 28

22–25 March 2021

These are the distributions of population trajectories from the model analyses that were used for the assessment. The top chart models the population in Management Area 1. This model used the two complete abundance estimates and the three estimates for Scoresby Sound multiplied by a factor to account for the portion of the population outside of the survey area. Also for Area 1 the pregnancy rate shown earlier and the age structure of the removals could be used to improve the correspondence of the model to the actual population. The solid line is the median projection, the dashed lines are the 5% and 95% percentiles of these distributions. The projections for 2020 and beyond assume the the recent levels of removals continue. As you can see the model shows a declining population and predicts that the population will be extirpated in 5 to 10 years if the removals continue as they are. Pregnancy rate and age structure data were not available for Areas 2 and 3 thus a simpler model was used which assumes that the population will only decline if the removals are too large.

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Parameter Estimates

Parameter	Area 1 Ittoqqortoormiit Scoresby Sound & south to 68°30’N	Area 2 Kangerlussuaq & 68°30’N to 67°N	Area 3 Tasiilaq & south of 67°N
2019 Population Size	410 (120, 992)	288 (136, 557)	206 (30, 669)
Current Growth Rate %/yr	0.1 (-1.0,1.9)	2.5 (0.3, 5.5)	2.6 (0.4, 4.9)
Depletion Level %	18.4 (5.8, 40.5)	27.0 (11.8, 58.2)	24.8 (3.8, 74.1)
1955 Population Size	2290 (1750, 2840)	1050 (723, 1540)	824 (578, 1210)

NAMMCO Annual Meeting 28

22–25 March 2021

These are the key parameters for the three Management Areas, the number is the median estimate and in parentheses are the 90% range of the distribution. The estimated population sizes for each area are small. The estimate for Area 3 is 206 which is based on the survey estimate from 2008, it is likely that this would be lower if there was an estimate from the 2016 survey. The working group discussed methods to use the lack of sightings with the survey effort to estimate the likelihood of various population sizes and recommended that this approach be developed for the next meeting.

The model estimated the median growth rate in Area 1 to be very close to zero and possibly negative indicating that the level of removals is not the only reason for the population decline. The growth rates for Areas 2 and 3 were estimated to be higher but as noted earlier these models did not include life history information and thus may be optimistic.

Each of these populations were found to be substantially depleted from much larger population sizes in 1955.

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Probability of Increase

Annual Removals	Area 1 Ittoqqortoormiit Scoresby Sound & south to 68°30’N	Area 2 Kangerlussuaq & 68°30’N to 67°N	Area 3 Tasiilaq & south of 67°N
1	0.57	0.94	0.88
2	0.48	0.86	0.76
3	0.4	0.79	0.66
4	0.32	0.72	0.58
5	0.28	0.65	0.52
6	0.22	0.57	0.46
7	0.18	0.5	0.41
8	0.15	0.44	0.36
9	0.13	0.37	0.33
10	0.11	0.32	0.29

NAMMCO Annual Meeting 28

22–25 March 2021

As in previous assessments the objective was to determine a level of annual removals that is sustainable and for narwhals we have used the criterion that the population should have a 70% probability of increase despite the removals. Note that for Area 1 there is no level of removals that would allow the population to increase with 70% probability, thus the WG concluded that no level of removals would be sustainable. For Kangerlussuaq the estimated probability of increase is 72% should 4 individuals be removed annually. The working group considered this estimate to be too optimistic because demographic variation, Allee effects, and other factors, which negatively affect small populations, as well as climate change were not included in the model but should be taken into account when considering the sustainability of the harvest. For Tasiilaq the estimated probability of increase is 76% should two individuals be removed annually. As for Kangerlussuaq this estimate is considered to be too optimistic, and additionally because of a statistical bias (the model abundance lacked a result from the 2016 survey). For Kangerlussuaq and Tasiilaq with the additional considerations, the WG concluded that no level of removals would be sustainable.

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Recommendations for �Conservation & Management

The NAMMCO SC seek an immediate response from managers to the information that current removal levels are unsustainable.
The NAMMCO SC develop guidance on a standard or principle-based approach for management and harvest advice for small stocks.
Data on struck and lost be obtained to inform assessments of sustainability if any harvest continues.
Reports of landed animals include the length of the animal in addition to the age category and presence of a fetus.
Hunters receive payment for assisting scientific research to clarify stock structure and abundance (e.g. through tagging animals).
Ways to improve the reporting of user observations (e.g. on struck and lost, pregnancies, stomach contents, and seasonal presence) be investigated to inform future assessments.
The negative impact of climate change on narwhals be recognized and included in management decision-making on all stocks.

NAMMCO Annual Meeting 28

22–25 March 2021