No dolphin – No fish
Recently on media we see a lot of news fabricated by fisheries cooperatives saying that the abundant of dolphin stocks are increasing in the Black Sea and Sea of Marmara. Seems like lobbying activities to legalize whaling, this news are full of false information. Unfortunately, heads of fisheries cooperatives representing the fishermen whose livelihood depend on the sea, are not only taking any responsibility in the protection of the biodiversity of our seas and sustainability of the fisheries but also misdirecting the public and government.
First of all; it is not clear which dolphin species they claim to be increasing. Three Cetacean species live in the Black Sea. These are Black Sea harbour porpoise (Phocoena phocoena relicta), bottlenose dolphin (Tursiops truncatus) and short-beaked common dolphin (Delphinus delphis). Also, it should be noted that when the commercial fish stocks are abundant, no one complains about dolphins but when the stocks are decreasing the dolphins are to blame. However, there are several factors affecting the stock abundance like natural annual or seasonal variations, marine pollution and red tides originated by toxic algae.
Scientific information on these intentionally false claims is as follows.
*Dolphins are not fish; they are mammals like humans, so they do not reproduce by laying millions of eggs like fish. Thus, they cannot reach abnormal numbers in seas.
Dolphins are mammals. Their pregnancies last 9 months as well and they nurse their newborns like humans. For example, bottlenose dolphins give birth once in 2-6 years and nurse their newborns 1,5-2 years. Females reach sexual maturity in 5-13 years, males reach sexual maturity in 9-14 years. They live approximately 25-30 years. So, it is not possible for them to reach abnormal numbers. Common dolphins gather in schools of nearly 1000 individuals during mating season to enrich the gene pool but those individuals come from different areas of the region.
*Between 1970-1983, 25.678 tonnes of dolphins were caught in Turkey. Commercial hunting of dolphins in the past is the main reason of the depletion of dolphin stocks in the Black Sea.
Mass hunting of dolphins reached its peak between the years of 1930-1950. Mass hunting of dolphins was forbidden in 1966 in USSR, Romania and Bulgaria and in 1983 in Turkey. However after the ban, between 1983 and 1991, cases of illegal killing have been reported occasionally. Just between 1970-1983, 25.678 tonnes of dolphins were caught in Turkey. It has been estimated that 1.5 million individuals from three dolphin species were caught by the Russian Empire and the Soviet Union in the Black Sea, in total 4-5 million were caught in the 20th century along with other countries. Due to this destructive overfishing, dolphin populations have been destroyed and came under threat of extinction excessively. Commercial hunting of dolphins in the past is the main reason for the depletion of dolphin stocks in the Black Sea.
* There are no millions of dolphins in the Black Sea.
It is very difficult to determine the size of dolphin populations, since they can be killed in large numbers in one day. The projection of a regional study to all of the Black Sea does not reflect reality. Therefore, only with the full participation of six countries, which have a coast on the Black Sea, this population census should be carried out. However, the required budget for this project could not be achieved in the last 10 years. In the summer of 2013, a research was carried out by both ship and plane within the territorial waters and exclusive economic zones (EEZ) (120,000 km2, approximately one-quarter of the Black Sea) of Bulgaria, Romania and Ukraine with participation of researchers from the Turkish Marine Research Foundation (TUDAV). But the results of the research will be published in 2014. Although the abundance of dolphin populations in the Black Sea is not known with certainty, it has been pronounced a few thousand for bottlenose dolphin (Tursiops truncatus), a few thousand to ten thousands for harbour porpoise (Phocoena phocoena relicta) and a few ten thousands for short-beaked common dolphin (Delphinus delphis) with recent research. Consequently, there is no millions of dolphins.
*A 40 meters long seine boat catches at least 4-6 tons of anchovy per day. The amount of fish that dolphins prey on can not be compared with these numbers.
It is well known that average 40 m long seine vessel catches at least 4 to 6 tonnes of anchovy only at a time. Despite this knowledge, the head of cooperative says that the amount of fish in the dolphin’s stomach is very high and this situation is highly thought-provoking. Mentioned numbers have nothing to do with reality. Depending on its species, a dolphin preys on amount fish which is 2% to 5% of its own weight in a day in average (approximately; harbour porpoise: 1 kg, short-beaked common dolphin: 3 kg, bottlenose dolphin: 7,5 kg). But if it finds this amount of fish. This amount varies according to time and place. When it can not find fish, the body needs are met from animal’s own adipose tissue. Moreover, according to the stomach contents analysis, we find dolphins who has empty and plastic bag filled stomaches.
*Dolphins in the Black Sea basin are losing their lives due to human intervention. Due to fishing with bottom nets, approximately 3.000 harbour porpoise and bottlenose dolphin species die every year.
Dolphins are killed by humans. Factors, which still threaten the dolphin populations in the Black Sea, are; by-catch, decrease in nutrients caused by habitat loss, marine pollution and mass deaths as a result of epidemics. By-catch is the most important human-induced causes of death for many marine mammal species. Especially due to fishing with bottom nets, approximately 3.000 harbour porpoise and bottlenose dolphin species die every year. In spring and at the beginning of summer, turbot fishing overlaps with birth and offspring nursing time of harbour porpoises. Offsprings’ of females, which dies in these nets, starve to death and wash ashore after a month. Moreover, due to food scarcity and pollution, dolphin’s sensitive immune systems collapse and they get sick. Like in 2003 and 2009, unknown mass deaths of dolphins were seen. Between 2003-2012, 647 live and dead dolphin strandings have been identified only in the western Black Sea.
*Dolphin fat do more harm on human health than benefit. Dolphins can not excrete heavy metals and chemicals from their bodies like terrestrial mammals, and these accumulate in the adipose tissues.
Dolphins, which are hairless mammals, can not excrete heavy metals and chemicals from their bodies like terrestrial mammals, and these metals and chemicals accumulate in their blubber. According to research in 1990, residues of pesticides such as DDT and HCH in Black Sea harbour porpoises’s bodies were quite higher compared to harbour porpoises living in other seas of the world. Consequently, dolphin fat do more harm to human health than benefit. Moreover, since oil and plastics sourced products are very common in this era, usage of dolphin fat in the industry is unnecessary and has no function at all.
*Overfishing, inaccurate fishery policies and marine pollution are main reasons for depletion of fish stocks and damages to fishermen.
Dolphins are the shepherd of the sea. If there is no dolphin, there is also no fish.
It is true and a common complaint about bottlenose dolphins attack fish in the nets. However, humans cause this problem not the dolphins. Such an interaction has not seen 20-30 years ago. Because of overfishing, marine pollution and inaccurate short-term fishery policies, we depleted the fish stocks. We did not think about the future when building a 65 meters long fishing boat in the semi-enclosed sea. Now, the coastal fishermen suffer the consequences of industrial fishing. Not just us, this problem has been experiencing all over the Mediterranean. Especially, setting another protection net with wider mesh size around the main net is useful in some areas. Dolphins are the shepherd of the sea. If there is no dolphin, it means there is also no fish.
As a result:
*After dolphin hunting has been banned in Turkey Seas since 1983, it is not possible to recover the populations. Since it has been estimated that abundance of bottlenose dolphin and short-beaked common dolphin populations are in an increasing trend for the last 30 years, this increase is low because of mass deaths and scarcity of food. As for harbour porpoises, due to by-catch and habitat loss, it is not possible to mention about the recovery of populations.
*Biodiversity protection is only possible by preserving all parts of the ecosystem. There were 26 commercially important fish species in the Black Sea in 1970’s, while today that number has dropped to 6. Dolphins, the top predators, are indicator species of the health of ecosystems. Reduction in dolphin populations damage not only the sustainable fisheries but also the whole ecosystem. Moreover, since dolphins prey more on elderly and sick fishes, they reduce the probability of fish populations to get sick and increase their reproductive success.
*Dolphin hunting is prohibited according to the Fisheries Act 1380. Turkey became a party to international conventions such as Barcelona, Bern and CITES, also, is on the point of signing the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic area (ACCOBAMS). According to these agreements, dolphin species were defined as strictly protected species. Black Sea populations (bottlenose dolphin and harbour porpoise: endangered (EN), short-beaked common dolphin: vulnerable (VU)) are on the IUCN Red List. “Black Sea Dolphins Protection Plan” started in 2006, whereas “Environment Protection and Rehabilitation of the Black Sea Strategic Action Plan” began in 2009. So, unleashing of dolphin hunting is not possible legally and scientifically under no circumstances.
*In order not to misdirect the public, it is important for fishery authorities to make explanations commonsensically and media members to take expert opinion while making the news.
*We’re hoping to see the days in which fishery cooperatives leave dolphins alone and make explanations about main issues such as overfishing, failure to comply with the ban on dolphin hunting, fry fishing and marine pollution and request Marine Protected Areas (MPAs) that are still not present in the Black Sea.
*We declare to the public that Turkish Marine Research Foundation (TUDAV) will always be the follower of this subject.
September 30, 2013
Turkish Marine Research Foundation (TUDAV)
A short-beaked common dolphin washed ashore in Kilyos in 2009.
A dead newborn harbour porpoise whose mother was probably killed in the turbot fishing.
A bottlenose dolphin, whose caudal fin was cut by fishermen, was caught by fishing nets incidentally.
Birkun A. Jr. 2008. The state of cetacean populations. (ed. T. Oğuz), State of the Environment of the Black Sea (2001-2006/7). Publication of the Commission on the Protection of the Black Sea Against Pollution (BSC), Istanbul, Turkey, pp. 365-395.
Bjørge A., Brownell Jr R.L., Donovan G.P., Perrin W.F. 1994. Significant direct and incidental catches of small cetaceans. (eds., W.F. Perrin, G.P. Donovan, J. Barlow) Gillnets and Cetaceans. Reports of the International Whaling Commission (Special Issue) 15, Cambridge, 629 p.
Öztürk A.A., Tonay A.M., Raykov V., Dede A. 2012. High mortality of harbour porpoise neonates in the southwestern Black Sea in 2010 and 2011. Abstract book of 26th Annual Conf. European Cetacean Society, Galway, Ireland. 90pp.
Öztürk B. 1996. Balinalar ve Yunuslar, Setelojiye Giriş. Anahtar Kitapları Yayınevi, Istanbul. 136p.(in Turkish)
Öztürk B. (Ed.) 1999. Black Sea Biological Diversity: Turkey. GEF Black Sea Environmental Programme, United National Publications, Newyork.27-35pp.
Tonay A.M., Öztürk B. 2003. Cetacean bycatches in turbot fishery on the western coast of the Turkish Black Sea. In Oray I.K., Çelikkale M.S., Özdemir G. (eds) International Symposium of Fisheries and Zoology (In memory of Ord. Prof. Dr. Curt KOSSWIG in His 100th Birth Anniversary), Istanbul, pp. 131 – 138.
Tonay A. M., Dede A., Öztürk A.A., Öztürk B. 2007. Stomach content of harbour porpoises (Phocoena phocoena) from the Turkish western Black Sea in spring and early Summer. Rapp. Comm. int. Mer Médit., 38: 616.
Tonay A.M., Dede A., Öztürk A.A., Ercan D., Fernández A. 2012. Unusual mass mortality of cetaceans on the coast of the Turkish Western Black Sea in summer 2009. J. Black Sea/Mediterr. Environ. 18:65-75
Tonay A.M., Dede A., Öztürk A.A., Öztürk B. 2012. Cetacean strandings in the Turkish Western Black Sea coast during 2007-2009. J. Black Sea/Mediterr. Environ. 18 (2):246-250
Tonay A.M., Öztürk A.A. 2012. Historical records of cetacean fishery in the Turkish seas. J. Black Sea/Mediterr. Environ. 18(3): 388-399.
Tonay A.M., Dede A., Öztürk A.A. 2013. 2003-2012 yılları arasında Türkiye’nin Batı Karadeniz kıyılarında karaya vuran yunusları izleme çalışmaları. 17. Ulusal Su Ürünleri Sempozyumu. 3-6 Eylül 2013, İstanbul.
Yel M., Özdemar E., Amaha A., Miyazaki N. 1996. Some aspects of dolphin fishery on the Turkish Coast of the Black Sea. In: (ed., B. Öztürk), Proceedings of the First International Symposium on the Marine Mammals of the Black Sea, İstanbul, pp. 31-40.
Zaitsev Yu., Mamaev V. 1997. Marine biological diversity in the Black Sea. A study of change and decline. Black Sea Environmental Series, Vol. 3. United Nations Publications, Newyork. ISBN 92-1-126042-6