Wednesday, June 29, 2011

Killing for Conservation?

Excellent stuff from Florida - again!


Top oceanic predators, especially large predatory sharks (TOPS), appear to be experiencing varying degrees of population declines. Life history data (e.g. diet, reproductive status, age and growth, mortality) are critical for developing effective conservation strategies for TOPS. Presently, lethal sampling remains the most effective and accurate means of gathering these data. To meet such challenges, many scientists have utilized specimens obtained from recreational and commercial fisheries, but have needed to supplement those data with fishery-independent sampling.

However, there is growing public and scientific debate as to whether lethal sampling of TOPS is justified for obtaining conservation data.
Here we describe the development and use of non-lethal alternatives for collecting data on (1) trophodynamics; (2) maturity state and fecundity; and (3) growth and mortality rates necessary to enact conservation measures for threatened or even data-deficient TOPS.


In the case of TOPS which are highly protected, lethal sampling is not an option.
As such, scientists have generated innovative non-lethal alternatives for obtaining data on trophodynamics, age-growth, maturity, and reproductive status. This is best exemplified in the white shark Carcharodon carcharias, which is designated as Vulnerable to Extinction by The International Union for Conservation of Nature (IUCN; Fergusson et al. 2005), listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), and fully protected in South Africa, Namibia, the USA, Australia, Israel, Italy, and Malta (Fergusson et al. 2005).

For example, white shark diet and feeding habits have been determined from gut content analysis of specimens obtained from fisheries (Cliff et al. 1989, Bruce 1992, Cortés 1999, Hussey et al. in press, Smale & Cliff in press). Sulikowski et al. (in press) recently developed non-lethal techniques to assess the reproductive biology of white sharks. Moreover, electronic tagging (Domeier & Nasby-Lucas 2008, Weng et al. 2007, Jorgensen et al. 2010), mark-recapture (Anderson et al. 2011), photo identification (Domeier & Nasby-Lucas 2007, Chapple et al. 2011), and application of molecular genetics (Gubili et al. 2009, Jorgensen et al. 2010) have been used to determine population size and structure of white sharks in a variety of locations.

In his book ‘Why big fierce animals are rare: an ecologist’s perspective,’ Colinvaux (1978) elegantly described how the second law of thermodynamics restricts the abundance and size of apex predators. He wrote: …Great white sharks or killer whales in the sea, and lions and tigers on the land…are very thinly spread. One may swim many lifetimes in the world oceans without encountering a great white shark… (p. 27) Even nearly a century ago, long before overfishing, Elton (1927) pointed out that large carnivores were rare.

Given the threatened status of many TOPS, there is a growing need to develop feasible alternatives to lethal sampling.
We recognize that this will not happen overnight; but as scientists, we need to become creative, collaborate, and challenge ourselves to do so, because this is the direction we need to be moving in, if conservation is our goal.

Finally, a voice of reason!
The above is from Killing for conservation: the need for alternatives to lethal sampling of apex predatory sharks, by Neil Hammerschlag and James Sulikowski and you can thankfully read the whole (short and clear, so do not worry) paper here.

I remain generally dead set against lethal sampling and must commend the authors for having tackled a subject that is highly controversial and for having unequivocally spoken out in favor of the animals. May I also add that it cannot be a coincidence that the first two people that are being acknowledged are DaMary and Jimmy, a clear tribute to their excellent advocacy for Sharks.
Be it as it may, kudos to everybody involved.

This is clearly the way forward and once again, you have positioned yourself very much at the forefront of Shark research and Shark conservation.

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