By Lowana Veal
REYKJAVIK (IDN) – One of the arguments for commercial whaling is that whales compete with humans for fish – they eat fish that would otherwise be available for human consumption.
According to Gísli Víkingsson from the Icelandic Marine and Freshwater Research Institute, whales eat around six million tonnes off Iceland, which is four to six times the amount taken by the Icelandic fishing fleet. “But of course it’s not all fish. Maybe a third is fish, though little is known for most species,” he says.
However, conservation biologist Joe Roman, from the University of Vermont, points out that several models have shown that the removal of whales and other marine mammals does not lead to increases in fish catches, and in some cases fishery yields have been increased in the presence of whales. He says that in some areas, such as the Caribbean, humans and whales consume considerably different marine resources.
Vikingsson and Roman were speaking at a symposium in Reykjavik in April, where Roman, who has been researching great whales in the South Pacific, argued that whales are actually beneficial to the environment, saying that great whales act as what he calls “ecosystem engineers”.
The term “great whales” encompasses 12 baleen whales – filter feeders which have baleen plates instead of teeth – and the sperm whale, which is a toothed whale.
“Great whales declined by about 85 percent during commercial whaling. However, since the whaling moratorium was adopted in 1982, whale populations have been recovering to different degrees. This has provided opportunities for research,” said Roman.
According to Vikingsson, who studies whales in the North Atlantic, “some of the main whale populations around Iceland, for instance fin and minke whales, have now reached about 80 percent of their pre-whaling size.”
“Whales provide ecosystem services such as climate regulation, enhanced biodiversity and evolutionary potential, enhanced primary productivity, tourism, whale meat provisioning, and culture and conservation,” Roman claims.
Whales often feed at depth but defecate near the surface. According to Roman, this pattern promotes the movement of deep-water nutrients to the surface, where they become available to algae, which rely on the sun for photosynthesis. This whale pump can provide nitrogen, iron and other nutrients essential to the growth of phytoplankton – microscopic algae.
These phytoplankton provide a food source for krill and other tiny marine organisms, which subsequently provide a food source for fish, whales and other marine mammals.
“Whales return around 24,000 metric tonnes of nitrogen per year to the surface of the Gulf of Maine, via faecal plumes and urine,” he told the symposium. Roman and his colleagues have focused much of their efforts on eastern North America, but other work shows similar patterns for the southern hemisphere.
Roman’s work concentrates on nitrogen and phosphorous in faecal plumes, while other researchers are looking at iron and other important nutrients for marine communities. In some areas, such as the Southern Ocean, iron is a limiting factor for primary production. When whales are producing blubber, they assimilate much less iron than usual, which means that their faecal plumes are high in iron.
Redistribution of nutrients also occurs when whales migrate from high-nutrient feeding areas to low-nutrient calving areas, which he calls the Great Whale Conveyor Belt, as they continue to release faecal plumes along the way. “This could increase primary productivity in low-nutrient zones by over 15 percent.”
Whales also contribute to carbon sequestration, which is one of the main mitigation factors for combating climate change. The biological pump focuses on phytoplankton, invertebrates and fish sinking to the bottom. When a whale carcass sinks, it brings a large pulse of carbon to the seafloor and provides a unique habitat, known as a whale fall.
Carcasses change over time and undergo four different stages of decomposition. Besides sequestering carbon, whale carcasses provide a habitat for more than 60 endemic species that are not found anywhere else. This has a positive impact on biodiversity at great depths.
Last year, the International Whaling Commission (IWC) adopted Resolution 2016-3 on Cetaceans and their Contributions to Ecosystem Functioning, which acknowledges the increasing volume of scientific research data that shows that whales enhance nutrient availability for primary productivity in feeding grounds rather than decreasing fishery yields.
The resolution states that because of their large size, “live whales represent an important store of carbon while their carcasses efficiently export carbon from the surface waters to the deep sea.”
The proposal was put forward by Chile but was co-sponsored by Argentina, Brazil, Costa Rica, Dominican Republic, Mexico and Uruguay.
The last paragraph of the proposal reads that the IWC “decides to increase collaboration and cooperation with governmental and non-governmental, regional, and international organisations to work on the contributions made by live cetaceans to ecosystem functioning issues, including the Commission for the Conservation of Antarctic Marine Living Resources, the Food and Agricultural Organisation of the United Nations, and the Convention on International Trade in Endangered Species of Wild Fauna and Flora, among others.”
Early in June, the United Nations is holding its high-level Oceans Conference in New York, with the aim of working towards Sustainable Development Goal 14 (SDG14) – Conserve and sustainably use the oceans, seas and marine resources for sustainable development. The conference coincides with World Oceans Day on June 8 and will include a proposal for an International Decade of Ocean Science for Sustainable Development from 2021-2030.
Topics at the conference will include marine pollution, the blue economy, ocean acidification, increasing scientific knowledge, ocean literacy and many other aspects related to SDG14. However, although the programme covers a wide range of topics, whales are hardly mentioned.
Arni Finnsson from the Iceland Nature Conservation Association, who has attended IWC meetings and was present at the symposium in Reykjavik at which Roman spoke, will also be attending the New York conference. Asked if the topic of whales as ecological engineers would be on the conference agenda, he replied, “Definitely not. Too sensitive and should be dealt with at the IWC.” [IDN-InDepthNews – 20 May 2017]
Photo: Humpback whales in North Pass between Lincoln Island and Shelter Island in the Lynn Canal north of Juneau, Alaska. This is a group of 15 whales that were bubble net fishing on 18 August 2007. Credit: Wikimedia Commons
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