TOPIC 23 Commercial seal hunt
Focus: Ecosystem
I am responible for searching the key issue of ecosystem. That is to say, the interplay of seal hunt and ecosystem will be researched and investigated.
Grey literature source (book, NGO documents, government documents)
1
David. Lavigne (2003). Marine Mammals: Fisheries, Tourism and Management Issues: CSIRO
Publishing, Collingwood, Victoria, Australia, “Marine Mammals and Fisheries: The Role of Science in the Culling Debate,” pp. 31-47
Seals are top predators, which is of paramount importance in the complex marine system. They eat fish, the target of fisherman, which makes fishermen want to kill their top competitor. However, the dramatic decline of fish stock is mostly due to the over-exploit in fishery. Increasing resource needs and technology improvement help fishermen stay longer in sea and catch more fishes with approach such as bottom trawling. Marine system loses a lot keystone species through this process, making it more difficult to maintain an ecological balance. It is not seal but human the reason of shrinking cod stock. However, because of the misunderstanding, 66% of the seal population was killed from 1990 to 2002. Dr.Lavigne carefully depicts the circumstance in sea, using logical arguments and concrete example to prove himself. It shows us a clear linkage between the fishery and seals, presenting with a high readability.
2
Paul Watson and the Sea Shepherd Conservation Society (2003) . Seal Wars- Twenty Five Years on the Front Lines with the Harp Seals Firefly Books
Seals not only eat cod but predators of cod, positioning multi trophic levels in complex food web. It also help maintain appropriate amount of plankton, which is a decomposer consuming fecal material. Without seals, plankton, krill, fish can not form a full food cycle, leading to energy and material loss in ecosystem. Especially, plankton will lack the source of organic material, creating a relatively sterile environment and destructing the ecosystem balance. Watson clearly stated the position and functions of seals, using ecological terminology, fair and objective tone to explain the importance of this vulnerable species and the interaction between environment and animals. It is also corroborated by other sources, gaining external consistency and support.
3
Johnston, Paul (2005 ). The Canada Seal Hunt:No management and no plan Greenpeace International ISBN: 90-73361-86-9, 978-90-73361-86-7 retrieved from http://www.greenpeace.org/international/PageFiles/25714/GP_Seals_def_lowres.pdf
This NGO document makes a strict critique to the seal hunt, listing a lots of data to support its view. It starts with the overview of seal conservation, following with the seal hunt and the interaction of ecosystem and seals. It criticizes that DFO(Department of Fisheries and Oceans) use a variety of unverified assumptions, which subject to large uncertainties to do the research. It use a lot of reference, concrete and consistent statistics to state that seal hunt has nothing to do with the cod stock recovery and it can not be justified, which is really convincing and of high credibility.
4
Melissa Cronin (2014). 7 reasons why Canada seal hunt need to end now retrieved from https://www.thedodo.com/7-reasons-why-canadas-brutal-s-548558738.html
The hunting of harp seal pups with whitecoats is illegal. However, the baby seal lose their white fur after two weeks old, which permits hunters to take action. This seriously hinder the reproduction of seals and will lead to an unstainable population.
Harp seals are not only crucial predators but also prey to orca whales. As a consequence, declining seal population prevent marine ecosystem from providing normal services, causing loss on other species as well as the entire ecosystem.
Besides the hunt, climate change is an amplifier of decreasing population. It is too fast for baby seals to adapt in water environment since the ice melts earlier and earlier. The combination of climate change and hunting might lead to catastrophe for the marine system.
Melissa clarified the reason why seal hunt need to end as soon as possible by speaking of externality, internal importance and the consequence. However, the tone of this article is a little bit subjective without a strong evidence backup, decreasing the credibility of this article.
5
(2007) Canadian seal hunt myths and realities Fisheries and ocean Canada,
ISBN 6624270764,9786624270760
In this government document, government consider seal hunt is sustainable and will not endanger the seal population. They promise the seal hunt is closely monitored and strictly regulated. And most importantly, they do not mean to recover the cod stock through seal hunt. The myths and realities in this article is totally opposite from the one in NGO’s article. It makes reader confused since data source and the method of data collection are not clearly stated. And it is really hard to decide which one is closer to the truth. Government’s article does give counterargument but it does not provide a convincing and objective rebuttal.
Peer reviewed sources (academic journals)
1
Johnston, D. W., Meisenheimer, P., & Lavigne, D. M. (2000). An evaluation of management objectives for canada’s commercial harp seal hunt, 1996-1998. Conservation Biology, 14(3), 729-737. doi:10.1046/j.1523-1739.2000.98260.x
There is a heated debate between government and NGO on the topic of seal hunt. Through biological population model and assessment in U.S, it was found out that the landed catches exceeded the allowable catch and the sustainable replacement yield. Human-caused mortality is much more than the potential biological removal levels, which makes seal hunt activity extremely risky from the perspective of steady population and ecosystem. This journal portrays a detailed process of model formulation and assessment procedure, declaring a powerful and convincing argument.
2
Hoover, C., Pitcher, T., & Christensen, V. (2013). Effects of hunting, fishing and climate change on the hudson bay marine ecosystem: II. ecosystem model future projections.Ecological Modelling, 264, 143-156. doi:10.1016/j.ecolmodel.2013.01.010
This journal reports a simulation test of varied levels of future impacts of climate change and marine animal harvest in varied levels. It is clearly showed that, with temperature rise and overexploit, marine mammals stocks is likely to be extirpated and a huge shift of food web will occur. The dominance in food web will change from benthic to pelagic, which benefits from the decline stocks of mammals and increasing sunlight. So the result indicates that it is better to pay less effort on marine mammals hunting. The report uses logical argument with models from different scenario, showing a clear picture of future impact of overfishing and climate change. This give a straightforward directivity in managing fishery and hunting.
3
Hammill, M. O., & Stenson, G. B. (2010). Comment on “towards a precautionary approach to managing canada’s commercial harp seal hunt” by leaper et al. ICES Journal of Marine Science, 67(2), 321-322. doi:10.1093/icesjms/fsp296
This journal argues that the fisheries management is in precise control, maintaining harp seal population near the highest level even during intensive hunting. It admits that the management does not include a simulation test and does not specify the catch limit algorithm to obtain an acceptable catch level. But it claims that we should not stand on the perspective of scientist but in industry. Industry can choose the specific quota to harvest they want while ensuring a healthy population of seal. It uses the government statistics to prove that the fishery management works well today. I remain skeptical for the statement since it use a useless loop to prove itself, referring government statistics to prove government management in good condition. It also lacks logical argument to show the credibility of the management system. The reason of the shift from management in high risk to well-managed system is not shown, which makes reader confused and less convinced.
4
Frie, A., Stenson, G., & Haug, T. (2012). Long-term trends in reproductive and demographic parameters of female northwest atlantic hooded seals (Cystophora cristata): Population responses to ecosystem change? Canadian Journal of Zoology, 90(3), 376-392. doi:10.1139/z11-140
This journal digs deeply into the interaction between seal population and ecosystem change. Due to the commercial seal hunt, the decline population of seal and climate change lead to ecosystem shift. In reverse, several ecosystem changes affect the seal reproduction. The extrinsic factors change in ecosystem has a causal relationship with female productive parameters and demographic parameters. It is shown clearly that the population pyramid of seal shifts from stationary structure from contracting structure since the juvenile seal is killed much frequently than the old. The correlation between single species and the entire marine ecosystem is clearly stated. The feedback loop is clearly shown in the journal with logically argument, so even the people with little prior knowledge can easily understand. As a result, it is a credible and useful source for my research.
Raw Data (graph and statistics)
1
Hammill, M. O., Heyer, C. E. d., Bowen, W. D., Canada. Department of Fisheries and Oceans.Science, Canada. Department of Fisheries and Oceans.Maritimes Region, Canadian Science Advisory Secretariat, & Canada. Department of Fisheries and Oceans.Québec Region. (2014). Grey seal population trends in canadian waters, 1960-2014. ( No. 2014/037.;2014-5701.;2014/037;). Ottawa, ON: Fisheries and Oceans Canada, Science.
There is a population estimation model for Sable Island, Coastal Nova Scotia (CNS) and Gulf of St. Lawrence (Gulf) seal herds. It predicts the overall population and also the amount of sustainable future removals for each herd. It also has the figure to show the uncertainty and risk of the current model when confronting mass mortality or huge environmental change. It also clearly states that higher harvest is related to high risk of population collapse.
Removals of grey seals
Decision table for the probability of respecting N70, N50 and N30 under harvest levels with different proportions of young of the year (YOY) in the harvest for the Gulf of St. Lawrence grey seals
2
Hammill, M. O., Canadian Government EBook Collection, Canada. Department of Fisheries and Oceans.Newfoundland and Labrador Region, Canadian Science Advisory Secretariat, & Canada. Department of Fisheries and Oceans.Québec Region. (2014). Abundance estimates of northwest atlantic harp seals and management advice for 2014. Ottawa: Canadian Science Advisory Secretariat.
The dataset showes the decline population of seal and the concrete number of commercial seal hunting. It also provides the repoductive samples of female seals, depicting that the age-specific pregnancy rate. But the amount of samples is not quite large, which contributes to the uncertainty of the estimate population and the hunting impact of seal.
Removal of seal in commercial hunting
Porportion of pregnancy
3
Environment Canada Ice Products Guide and Canadian ice service retrieved from http://www.ec.gc.ca/glaces-ice/default.asp?lang=En&n=D32C361E-1
The raw data and graphs from Environment Canada of ice cover rate clearly shows that ice coverage is much lower than the mean average before. It also turns out that current ice condition is as an average of 80% of the 1979-2000 mean. With the external environment change, the population of seal will change subsequently.
