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Abstract

There's no doubt that swimming with whale sharks is a fabulous experience. It's interesting, however, how our perception of sharks has changed and now swimming with the biggest shark can connect us to our oceans. Looking into the future, no one could have expected that this activity would contribute to local economies, like in La Paz Bay. In the late 90's you could see whale sharks around La Paz Bay on route to one of the popular islands in the area. By the 2000's some people started providing trips, offering the experience of swimming with the biggest fish on Earth. Problems occurred as a result of increased boat traffic coupled with a lack of guidelines to perform the activity. La Paz city is one of the most highly populated coastal areas in the Gulf of California and has the highest growth rate (2.6%) in the state. Whale shark tourism has also increased, from 26 authorized boats in 2006 to 109 in 2013. In contrast, the mean of the yearly abundance of sharks is 56, highlighting a capacity building issue. This is evidence that the whale sharks represent an important part of the economy of the city, and presents us with a challenge to protect it. InLa Paz Bay we have maintained a whale shark monitoring program since 2004. Studies include abundance, fidelity, seasonality and injury analysis. Injury analysis from 2004–2008 showed that up to 54% (18 of 33) of sharks had been hit by boats. In 2006, with the collaboration of the Mexican government, a Code of Conduct was generated for whale shark tour operators. In order to enforce the management, each year since 2009 the tour operators are trained and a dissemination program is designed with the aim of communicating the code of conduct with a focus on private boats. The success of the management is measured by fresh injury analysis. Betweenseasons 2004/2005–2014/2015, 380 whale sharks were identified; of these, 49 (22.3%) returned between years. During the season, sharks spend periods of between 40–70 and up to 200 days in the area before leaving the Bay. Seasonality varied in some years but the common season runs from September to February. Without considering the extreme years, the abundance per year is estimated from 20 (95% CI =16–31) to 71 (95% CI= 65–85, 95% SS) sharks, with a mean of 56. Fresh injury analysis from 250 identified sharks, 135 (54%) had fresh injuries present. Of these, 60% were abrasions, 30% both abrasions and lacerations, and 9% had only lacerations. The trained personal from the tourism companies has increased from 33 in 2009 to 88 in 2014. From 2009–2012 careful monitoring of the whale shark population revealed that the affected sharks decreased by 26% (from 61 to 35%). Although these numbers increased again over the last two years, up to 64% (70 of 109 sharks) during the 2014/2015 season, this was perhaps because the sharks remained in the Bay for a longer period of time. Morethan 10 years of monitoring have been key to establishing La Paz Bay as a critical habitat of the species, which needs to be protected. This study has been helping to measure the success of the management, which still needs to be enforced by the government and engaged by the community. The changes in abundance and seasonality need to be considered for a carrying capacity study. When tour operators and the community are engaged in promoting the rules it can reduce harm to whale sharks, as in 2009–2011. The increase in permits and lack of enforcement will increase negative effects on whale sharks.

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/content/papers/10.5339/qproc.2016.iwsc4.47
2016-05-15
2019-12-06
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