30 April 2013

Awesome Non-fish in Trouble # 5: World's smallest whale population

Photo by Robert Pitman from ARKIVE

The Northern Pacific Right Whale, Eubalaena japonica, is found in Northern Pacific waters around the Sea of Okhotsk, Bering Sea, Gulf of Alaska, and eastern Aleutian Islands.[1] It is an Endangered species according to the IUCN Red List.  Having been a fish species since the 1500s, it was heavily exploited in the 1800s and illegally caught by Soviet whalers in the 1900s.[2] It is currently considered as the world's smallest whale population. For instance, the Bering Sea population is composed of only 8 females and 20 males, and the Western Pacific population may not be larger.[3] Current threats include ship strikes, entanglement in fishing gear, and possibly disturbance from seismic activities.[3]

To know more about the Northern Pacific Right whale, visit SeaLifeBase.

[1] Shelden, K.E.W.; Moore, S.E.; Waite, J.M.; Wade, P.R.; Rugh, D.J. (2005) Historic and current habitat use by North Pacific right whales Eubalaena japonica in the Bering Sea and Gulf of Alaska.
Mammal Review 35(2):129-155.

[2] Clapham, P.J.; Good, C.; Quinn, S.E.; Reeves, R.R.; Scarff, J.E. (2004) Distribution of North Pacific right whales (Eubalaena japonica) as shown by 19th and 20th century whaling catch and sighting records. Publications, Agencies and Staff of the U.S. Department of Commerce. Paper 95.

[3] Wade, P.R., et al. (2011) The world's smallest whale population? Biology Letters 7:83-85.

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29 April 2013

Fishing the little fish

What is forage fish? In the marine food and energy pyramid, they are the small to medium-sized schooling pelagic fish feeding on phytoplankton, i.e., primary consumers or grazers; or secondary consumers if they feed on zooplankton. Forage fish are prey to bigger fishes, like tuna and sharks; and marine mammals such as whales and sea birds. Because of the growing demand by fisheries, about 30% of the worldwide marine fish landings for aquaculture, livestock, human consumption and fish oil, forage fish are now in trouble of depletion [1]. The question now arises, what would be its ecological impact if this continues?

Over exploitation may result to decline in recruitment or reproductive success of both forage fish and its predators. As evidence, studies on large fish and marine mammals have shown decline, simply because of lower prey abundance [2]. In layman's term, if we continue to exploit the "little fish", sooner or later there will be no more "big fish" for us to catch and consume. So as early as today, we should push through ecosystem-based fishery management that will surely sustain the future generations of our kind.

Let us help spread the knowledge of conservation for a better future.

To know more about fishes, visit FishBase; and to know more about marine mammals, visit SeaLifeBase.

[1] Alder, J., Campbell, B., Karpouzi, V., Kaschner, K., and Pauly, D. 2008. Forage Fish: From Ecosystems to Markets. Annu. Rev. Environ. Resour. 33:153-166.

[2] Pikitch, E., Boersma, P.D., Boyd, I.L., Conover, D.O., Cury, P., Essington, T., Heppell, S.S., Houde, E.D., Mangel, M., Pauly, D., Plagányi, É., Sainsbury, K., and Steneck, R.S. 2012. Little Fish, Big Impact: Managing a Crucial Link in Ocean Food Webs. Lenfest Ocean Program. Washington, DC. 108 pp. 

Note: Video and image credits to PEW.

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06 April 2013

Deception in the distant seas

The adage Honesty is the best policy applies to almost everything, including fisheries sciences. Apparently, more than 90% of the marine catches in the African waters by China's "giant" fishing fleet is not officially reported to UN's Food and Agriculture Organization (FAO).

Pew Ocean Science Division of The Pew Charitable Trusts.

This supposed gross misrepresentation of numbers, not only by China but by many countries as well, greatly impacts the creation of management plans that bases its data from FAO. Clearly, using wrongful statistics results to ineffective management plans which can lead to further depletion (and eventually extinction) of fisheries stocks.

Mega trawlers in West African waters. Source

For more details, click here or read the full paper here.

Web Update - April 2013

Our website http://www.sealifebase.fisheries.ubc.ca/ is now updated.

Search for your favorite non-fish marine species now. Happy learning!

05 April 2013

An unbreakable bond

 The strong bond between mother and calf is hard to break. In Dana Point, California, a female bottlenose dolphin (Tursiops truncatus) was seen carrying its dead calf on its back as observed by whale watchers (see March 2013 video). This behavior is also exhibited by pilot whales (Globicephala macrorhynchus/melas), and rough-toothed dolphins (Steno bredanensis) among others. [1, 2, 3] Some researchers say this is their way of mourning.

Dolphin pods exhibit this behavior within their feeding areas in the wild. [3] Mann and Watson-Capps (2005) report that mothers foraging behavior are likely during separations with their calves. Most calf mortalities happen when poor calf condition is directly affected by the maternal condition and experience during the weaning and nursing process. [4] Since observations of this behavior are often seen by whale watchers in feeding areas, it is possible that tourism may have disrupted the foraging of mothers, decreasing their maternal condition, resulting in poor calf conditions or even death.

To know more about dolphins, visit SeaLifeBase.


[1] Ritter, F. (2007) Behavioural responses of rough-toothed dolphins to a dead newborn calf. Marine Mammal Science 23(2):429-433.
[2] Caldwell, M.C.; Caldwell, D.K. (1966) Epimeletic (care-giving) behavior in Cetacea. Pp. 755-789 In K.S. Norris (ed) Whales, dolphins and porpoises. University of California Press, Berkeley and Los Angeles, CA.
[3] Harzen, S.; Dos Santos, M.E. (1992) Three encounters with wild bottlenose dolphin (Tursiops truncatus) carrying dead calves. Aquatic Mammals 18:49-55.
[4] Mann, J.; Watson-Capps, J.J. (2005) Surviving at sea: ecological and behavioural predictors of calf mortality in Indian Ocean bottlenose dolphins, Tursiops sp. Animal Behaviour 69(4):899-909.

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