{"id":4557,"date":"2015-03-24T09:40:07","date_gmt":"2015-03-24T13:40:07","guid":{"rendered":"https:\/\/www.bates.edu\/biology\/?p=4557"},"modified":"2024-01-04T16:17:50","modified_gmt":"2024-01-04T21:17:50","slug":"tuna-and-oyster-overfishing","status":"publish","type":"post","link":"https:\/\/www.bates.edu\/biology\/2015\/03\/24\/tuna-and-oyster-overfishing\/","title":{"rendered":"Tuna and Oyster Overfishing"},"content":{"rendered":"

BIO 209<\/p>\n

Student Blog Series<\/p>\n

Katie Williams<\/p>\n

\"Bigeye<\/a>

Bigeye tuna are fished via huge purse-seine nets. This fishery could be more sustainable with different fishing practices including the depth and location of fishing. Photo from tunaseiners.com.<\/p><\/div>\n

For my presentation on a scientific paper in \u201cGlobal Change in Marine Systems\u201d, I looked at a scientific paper titled the \u201cEffects of Gear Characteristics on the Presence of Bigeye Tuna (Thunnus Obesus<\/em>) in the Catches of the Purse-Seine Fishery of the eastern Pacific Ocean.\u201d The paper, written by Cleridy E. Lennert-Cody, Jason J. Roberts, and Richard J. Stephenson, explored the effects of gear characteristics on the catch of bigeye tuna to motivate a search for a practical means of reducing the catch of bigeye tuna. The most recent stock assessment for bigeye tuna indicates that fishing mortality remains too high to maintain a stable bigeye tuna population. In contrast, the skipjack tuna population remains healthy and stable. Therefore, a management goal has been to find means of reducing catches of bigeye tuna in the purse-seine fishery on floating objects while minimizing losses of skipjack tuna catch. Modifying gear characteristics of the purse-seine nets may reduce bigeye tuna catch because the two different species of tuna typically inhabit different depths around the nets. Bigeye tuna tend to be found in deeper water than the skipjack tuna. Thus, the study focused on gear characteristics related to the fishing-depth of the purse-seine and the length of material hanging below the floating object at the top of the net\/purse-seine. The paper\u2019s analysis of the presence\/absence of bigeye tuna catch in purse seine nets from 2001-2005 found that object depth of the purse-seine and location were most significant. Thus, the paper concluded that fishers can alter their fishing practices and reduce the amount of bigeye tuna being caught in their purse-seine nets by a) changing object depth b) changing the overall depth of the hanging material from the object and c) changing the overall location.<\/p>\n

Dave Kurey<\/p>\n

\"Oysters<\/a>

Oysters in the Chesapeake Bay have been depleted by overfishing. Population growth is limited by disease and sedimentation. Photo credit Mark Godfrey \u00a9 2009<\/p><\/div>\n

For my segment of the presentation, I discussed at the scientific paper \u201cDecline of the Chesapeake Bay oyster population: A Century of habitat destruction and overfishing.\u201d\u00a0 This paper, written by B.J. Rothschild, J.S. Ault, P. Goulletquer, and M. Heral is about the declining oyster populations in the Chesapeake Bay.\u00a0 They start out by giving a brief background on the industry since the early 1800s and how the oyster harvest levels have fluctuated.\u00a0 After discussing a variety of different reasons from current literature that explain the decline in oyster populations such as reduced water quality, diseases in the bay, and pollution, they offer their own reasoning.\u00a0 This paper argues that there are two other reasons that are actually much more detrimental. The two main reasons they blame for the decline in oyster population are harmful fishing practices and overfishing.\u00a0 The harmful fishing practices, they found, are a result of both an increase in technology and people capitalizing on an opportunity to make money.\u00a0 The technology became more efficient over a 200-year period with hand tongs during the 1800s, oyster dredges in 1865 when it became legal and then hydraulic tongs in the 1900s.\u00a0 They found that over the years, the techniques became more invasive and more damaging to oyster bars.\u00a0 Essentially, they argue that these more mechanized ways of harvesting oysters have leveled oyster bars.\u00a0 The methods they used were superimposing the data from 3 different studies during different time periods ranging from 1907 until the 1990s.\u00a0 All of these studies focused on total oyster bar area, known as \u201cshelled area,\u201d on the Choptank River Lighthouse Oyster Bar.\u00a0 After superimposing the data, they plugged it into a growth model to asses oyster bar growth.\u00a0 This provided them with a stock assessment that gave them yield per recruit and average density.\u00a0 They found that over the 3 studies, from 1907 until 1990, there was a 52% decline of oyster habitat.\u00a0 To put that in perspective, during the 1907 study, 25% of the entire bay was considered to be oyster bar habitat.\u00a0 Given these results, and the consideration of the fishing techniques they looked at, they offer a 4-point management strategy.\u00a0 This four-pronged strategy involves fishery management, repletion, habitat replacement, and implementing a broodstock sanctuary.\u00a0 Although not implemented yet, these scientists argue that for economic, water quality, and biological reasons, the oysters need to be protected because of past exploitation that occurred as a result of technological improvements.<\/p>\n","protected":false},"excerpt":{"rendered":"

BIO 209 Student Blog Series Katie Williams For my presentation on a…<\/p>\n","protected":false},"author":478,"featured_media":4558,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_hide_ai_chatbot":false,"_ai_chatbot_style":"","associated_faculty":[],"_Page_Specific_Css":"","_bates_restrict_mod":false,"_batesModPostContentOverride_prepend":false,"_batesModPostContentOverride_append":false,"_batesModPostContentOverride_append_before_footer":false,"_table_of_contents_display":false,"_table_of_contents_location":"","_table_of_contents_disableSticky":false,"_is_featured":false,"footnotes":"","_bates_seo_meta_description":"","_bates_seo_block_robots":false,"_bates_seo_sharing_image_id":0,"_bates_seo_sharing_image_twitter_id":0,"_bates_seo_share_title":"","_bates_seo_canonical_overwrite":"","_bates_seo_twitter_template":""},"categories":[1],"tags":[],"class_list":["post-4557","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/posts\/4557","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/users\/478"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/comments?post=4557"}],"version-history":[{"count":2,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/posts\/4557\/revisions"}],"predecessor-version":[{"id":7533,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/posts\/4557\/revisions\/7533"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/media\/4558"}],"wp:attachment":[{"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/media?parent=4557"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/categories?post=4557"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bates.edu\/biology\/wp-json\/wp\/v2\/tags?post=4557"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}