Caribou herd dynamics: impact of climate change on traditional and sport harvesting

Transcription

1 Canadian Eastern Subarctic IRIS Caribou herd dynamics: impact of climate change on traditional and sport harvesting Steeve D. Côté Université Laval C. Hins, M. Festa-Bianchet, C. Dussault, J.-P. Tremblay, V. Brodeur M. Simard, J. Taillon, M. Le Corre, S. Sharma

2 Importance of caribou for traditional and sport harvesting Traditional harvesting Aboriginal communities have a strong cultural connection to caribou. The most important terrestrial subsistence resource for indigenous people. In northern Québec and Labrador, subsistence hunters harvest about 15,000 caribou each year. Outfitting industry and sport hunting In northern Québec: nearly 100 outfitting businesses, sport hunters each year. Caribou sport hunting generates $20 million in annual revenues for a total economic impact exceeding $30 million.

3 Importance of caribou for traditional and sport harvesting Impact of climate change on subsistence and sport hunting activities Weather conditions are critical for the selection of seasonal migratory routes and winter grounds, affecting hunter success. Long-term climate change may affect access to hunting grounds, e.g. by changing the timing of freeze-up and break-up of large bodies of water. If climate change alters the distribution of caribou away from northern villages and outfitting installations, hunting may become increasingly difficult.

4 Caribou herd dynamics Northern Québec and Labrador Tow migratory caribou populations Rivière-aux-Feuilles herd (RAF) Rivière-George herd (RG) Large seasonal migrations (over hundreds of km) In spring, to reach calving grounds in the tundra In fall, to reach winter range in the taiga. Rivière-aux-Feuilles Rivière-George

5 Caribou herd dynamics Northern Québec and Labrador General declines of migratory and sedentary populations throughout North America Large population fluctuations in recent decades Population size (x10k) Year

6 Past and current variation in demography Survival and mortality In 1984, adult female survival was 95% (Messier et al. 1988) From , preliminary analyses of survival of radio-collared caribou in both herds indicate: yearling survival was only 69% adult female survival was 82% (87% if hunting mortality is excluded) adult male survival was 51% (65% if hunting mortality is excluded)

7 Past and current variation in demography Reproduction In most species, females have high pregnancy rates, typically over 90% (Gaillard et al. 2000) In northern Québec-Labrador, productivity appears to be high when populations increase (90%) and lower when populations decline (70%) (Couturier, Côté et al. 2009, Can J. Zool.) For RG herd, when the population declined, pregnancy rates of females aged 4 years declined from 96% to 82%, but for females aged 2 or 3 years the decline was from 77% to 24% (Bergerud et al. 2008)

8 Past and current variation in demography Recruitment rate Calf to female ratios have been lower in recent years in both herds, compared to ratios observed in the George herd during the increase phase in the 1980s.

9 Impact of climate change on herd dynamics Migration routes Timing of migration and freshwater ice formation: Increasing risk of massive mortality associated with crossing rivers and reservoirs. Delay in migration to avoid ice-free bodies of water: possibly reducing reproductive success, as females might not be able to reach calving grounds on time and be forced to calve in suboptimal sites. Higher temperatures and change in the snowfall regime: Lower resource availability, increased energy expenditures, lower body condition, ultimately effects on population dynamics.

10 Impact of climate change on herd dynamics Mismatch in the timing of calving and forage availability Warmer springs leading to earlier onset of plant growth Annual timing of calving is less variable than plant growth Relationship between the timing of calving and forage availability could be affected by changes in the timing of green-up and the length of the growing season

11 Impact of climate change on herd dynamics Mismatch in the timing of calving and forage availability High Low recruitment

12 Impact of climate change on herd dynamics Mismatch in the timing of calving and forage availability Production and survival of young reindeer in Greenland are negatively affected by plant phenology Index of mismatch between trophic levels Post & Forchhammer (2008) Phil. Trans. R. Soc.

13 Adaptability to changes in caribou populations Population monitoring and assessment, harvest rate New management plan, HFTCC Hunting caribou in the future: managers, stakeholders and communities should be prepared for a lower abundance of animals and perhaps a less predictable distribution away from communities

14 Supporting agencies