Bottom Trawling

PHOTO BY SAVE OUR SEA FOUNDATION

Bottom trawling is a industrial fishing method whereby huge nets with heavy weights are drag across the seabed, scooping up everything in its path. This method is usually used in catching fishes that live on the seafloor, such as shrimp, cod, sole and flounder (Marine Conservation Institute, 2014).

One consequence of bottom trawling is that it rakes up large amount of sediments on the seabed, which adsorbs contaminants in the ocean. Frequent trawling causes plume of sediment floating above the seabed and can be seen from pictures captured from the sky. Research has shown that marine life (such as mussels, benthic, prawns and flatfish) living on the seabed are particularly at risk as they end up adsorbing the contaminants ( European Commission, 2012). 

Landsat image showing pervasive sediment plumes

PHOTO BY SKYTRUTH

Another impact of bottom trawling is its destruction to the seabed habitat. The method is unselective and besides the targeted species, many other species are caught and thrown away as by-catch. Corals, which serves as a habitat for many other marine life, dominate the by-catch, leaving the ocean floor bare. Since coral reefs are estimated to only grow by millimeters per year (Tracey et al, 2007), recovery of coral ecosystem will be very slow. This leaves the marine ecosystem permanently damaged. 

PHOTO BY NOAA

 References:

Marine Conservation Institute. (2014). Destructive Fishing. [ONLINE] Available at: https://www.marine-conservation.org/what-we-do/program-areas/how-we-fish/destructive-fishing/. [Accessed 29 September 14].

European Commission. (2012). Pollutants released by seafloor trawling affect marine life . Science for environment policy, [Online]. 309 (12). Available at:http://ec.europa.eu/environment/integration/research/newsalert/pdf/309na3_en.pdf [Accessed 29 September 2014].

Tracey D.M. et al. (2007) Deep-sea scleractinian coral age and depth distributions in the northwest Atlantic for the last 225,000 years. Bull Mar Sci 81:371–391

SHARKS!

Oceanic white-tip killed for their fin.

PHOTO BY ANDY CORNISH

Today i was just browsing through BBC news and came across the article "First ban on shark and manta ray trade comes into force". 5 types of sharks are protected under the ban - the oceanic white-tip, the porbeagle and three other species of hammerhead sharks.

It is surprising how long it took for the ban to come into place. According to McGrath, efforts against unregulated trade of sharks started since the 1990s but only managed to be achieved last year at the Cites meeting in Bangkok.

Due to increased shark attacks in western Australia, 172 sharks were culled in a 13 week trial, of which none of the 172 caught was a white shark (BBC, 2014). Also, shark's fin soup is a traditional Chinese dish that serves as a symbol of status and wealth. In the past, Chinese believed that the absence of shark's fin soup at a wedding is an indicator that the bride is marring into a poor family. Although people know that it is not true now, 2 out of 3 recent wedding dinners that i have attended still serve shark's fin.

Shark's fin soup

PHOTO BY PAUL HILTON

After watching Jaw by Steven Spielberg at the age of 8, I really hated sharks and would gobble up shark's fin (although its tasteless), hoping to kill all the sharks in the world. Its all in the past now and I refrain from eating it whenever I can. When planning my sister's upcoming wedding dinner, we requested the restaurant to swap shark's fin with crab meat. Hopefully our younger generation will discard the traditional thinking that we must have shark's fin at weddings.

References: 

BBC News. (2014). Matt McGrath: First ban on shark and manta ray trade comes into force. [ONLINE]. September 2014. Available at: http://www.bbc.com/news/science-environment-29175592. [Accessed 14 September 2014]

BBC News. (2014). More than 170 sharks caught under Australia cull policy. [ONLINE]. May 2014. Available at: http://www.bbc.com/news/world-asia-27304580. [Accessed 14 September 2014]

Love seafood??

For seafood lovers, it is always good when the fish is big, so that there is more for everyone, isn't it? The bigger the better! But if everyone thinks that way, we are going to keep fishing the big fishes.

We have already consumed 90% of the big fishes- turtles, tunas, sharks and whales (Earle 2009). Even the small fishes are depleting due to bottom trawl fisheries. Before young fishes gets to grow big, we fish them out.

World hunger is not a problem of production but that of distribution. For every 1 pound that reaches the market, 100 pounds gets thrown away as bycatch (Earle 2009). A simplified illustrated of the extent of wastage is that for every 1 sardine you eat, 300 gets thrown away(rough estimation using the average weight of sardine given by Washington Department of Fish and Wildlife). If we are not careful and continue unsustainable fishing, world hunger would turn into a problem of  production when there no more fishes in the ocean.

PHOTO BY WESTERN SAHARA RESOURCE WATCH

References: 

Earle. S. 2009. TED: My wish: Protect our oceans. [Online Video]. February 2009. Available from:http://www.ted.com/talks/sylvia_earle_s_ted_prize_wish_to_protect_our_oceans. [Accessed: 20 August 2014]

Washington Department of Fishing and Wildlife. 2011. Purse Seine Fishery for Pacific Sardine- Sardine Biology. [ONLINE] Available at: http://wdfw.wa.gov/fishing/commercial/sardine/biology.html. [Accessed 11 September 14].

Plastic sea

PHOTO BY NORBERT WU 

Since my previous post in on plastics, I shall continue with another post on plastic pollution. According to Captain Charles Moore, 90% of the trash found in the Great Pacific Garbage Patch is plastic. The Great Pacific Garbage, also known as Trash Vortex, lies between Hawaii and California. Litter gets pick up by ocean gyre current and get deposited in the centre of the gyre, where it is relatively calm. The circular motion of the gyre current traps and prevents litter from escaping, resulting in an accumulation of ocean debris. Although most debris may be small and very noticeable, the Pacific Trash Vortex is estimated to be larger than Texas (NOAA, 2013). 

SOURCE: GREENPEACE

The tricky part to cleaning up our mess is how not to further harm marine wildlife. Angelicque White, a scientist from Oregon State University, points out that plankton will be remove from the ocean when we try to fish out all the trash, thus further affecting the marine ecosystem. Why than should we go through all the complicated measure when we can start reducing our waste instead?

"The problem is that the barriers to gyre cleanup are so massive that the vast majority of the scientific and advocacy community believe it’s a fool’s errand – the ocean is big, the plastic harvested is near worthless, and sea life would be harmed. The solutions starts on land" (Wilson, 2013)

References:

NOAA (2013). How Big Is the "Great Pacific Garbage Patch"? Science vs. Myth. [ONLINE] Available at:http://response.restoration.noaa.gov/about/media/how-big-great-pacific-garbage-patch-science-vs-myth.html. [Accessed 05 September 14].

Wilson, S. (2013). The Fallacy of Cleaning the Gyres of Plastic With a Floating "Ocean Cleanup Array" Read more: The Fallacy of Cleaning the Gyres of Plastic With a Floating "Ocean Cleanup Array" . [ONLINE] Available at: http://inhabitat.com/the-fallacy-of-cleaning-the-gyres-of-plastic-with-a-floating-ocean-cleanup-array/. [Accessed 05 September 14].