Deciphering Philopatry - good or bad Science?

Great HH with one of Neil's new tags.

Want to go and catch yourself some Salmon Sharks?
Nothing could be easier: go fishing in the Northern Gulf of Alaska in November - and bingo! And if you believe that the fishermen have not long discovered the TOPP tracks - think again!

As Juerg writes in his correspondence to Nature.

Two faces of marine ecology research

The ecology of animal movement is one field that would benefit from sound evaluation of the risks, benefits and ethics of its important research findings (Nature 484, 415 and Nature 484, 432–434; 2012 read it!).

Scientists can now track the complex horizontal and vertical movements of a wide range of marine species, including tuna, sharks and turtles. These results reveal biodiversity hotspots and inform conservation policies by providing insight into animal behaviour and ecology. However, they also guide fishing operations towards resource-rich locations — putting further strain on both target and by-catch species.

Too many species face severe stock depletion because of intense fishing, pollution and other anthropogenic pressures. The detrimental implications of marine ecological research results must be acknowledged.

Juerg Brunnschweiler
Swiss Federal Institute of Technology (ETH Zurich), Zurich, Switzerland.
But there is of course also this.

It is possible, by marrying electronic tag data with oceanography, to gain a sufficient understanding of ecosystem function to enable more effective management of ocean resources.
Specifically, this study shows that when bluefin tuna enter the Gulf of Mexico, they are going to specific locations, where cool, productive water in “cyclonic eddies” makes its way along the continental slope. So during April and May, when they are spawning, bluefin tuna are relatively concentrated – whereas yellowfin tuna remain disbursed broadly throughout the Gulf.

This suggests that it would be possible to protect the bluefin, which are accidentally caught on longlines intended for yellowfin, by restricting fishing in those specific areas where the bluefin are spawning; but that such restrictions need not reduce yellowfin catch rates since they are more uniformly distributed.

Or this.

Great white sharks are found in waters all around New Zealand. National Institute of Water and Atmospheric Research (NIWA), and Department of Conservation (DOC) scientists are investigating the long distance movements of great white sharks inside and outside New Zealand’s territorial waters to improve our understanding of their species’s migratory patterns.
It will assist with designing management measures to reduce shark bycatch in fisheries.

Niwa principal scientist Malcolm Francis said despite the process sounding rough, the safety of the sharks was at the heart of the project.
As part of a wider study which began in 2005, it is hoped the research would return population figures and migratory behaviour of the protected species to assess how many sharks were being killed in fishing nets and lines.

Yes it looks like we got ourselves an ethical debate!
But maybe not so much - and whilst you're pondering, here's a rather epic video about that GW tagging in New Zealand.
Enjoy!



So what about those tracks.
As Bob Hueter already stated in 1998,

I consider the issue of philopatry and natal homing in sharks to be the most important issue in shark biology today, and I challenge all shark researchers to test this hypothesis rigorously in their respective research areas.

Nearly every type of shark research can play a role in this, for the ramifications of philopatry, if true for most shark species, would be profound. It certainly would affect our views of shark evolution and genetics, and it would shape new perspectives on the physiology and ecology of shark species. It would fundamentally affect studies of shark population dynamics, and perhaps most importantly, it would drastically change conventional views of shark fisheries science for the management and conservation of shark populations.

Hundreds of thousands of dollars and thousands of tags later, we now know this.
Sharks and Fishes are not randomly distributed throughout the oceans. Instead, they frequent well determined seasonal, behavior-, gender- and age-related hotspots and travel between these focal points on well determined marine highways.
Or as Hueter and Heupel write in 2004 (read it, this is seminal stuff!)

Many shark species are highly migratory, some covering thousands of miles of ocean in a single year.
However, with the emerging evidence of philopatry in various shark species, it would be wise from a conservation and management perspective to not view this group of marine fishes as oceanic nomads, but rather as more sophisticated, long-distance travelers with a number of discrete homes in the sea. How precise those homes are will need to be established with further research and analysis.

For us Shark conservationists, those data about philopatry are absolutely vital.
As I've tried to show here, many Sharks continue to fall victim to incidental catches despite of being protected, something that can be countered by establishing seasonal localized fishing bans; and like in the case of Playa or, say Vietnam, those localized and seasonal measures may be easier to achieve than trying to enact blanket protection of a species year-round and country wide.

This I believe is also the next step after having established those Shark sanctuaries.
With the big announcement hopefully looming, we're consequently already mulling the next big project that is hopefully going to lead to the full protection of the Shark nurseries, and thus of the valuable big pregnant females during the birthing period.
Keep watching this space!

But what about those published tracks?
Are those publications, maps, interactive websites and apps not simply showing the way for anybody wanting to go and kill the animals? And there is of course also the Anthropogenic Allele Effect, specifically the possible impact of poorly regulated tourism on the animals once newly discovered hotspots are being publicized - like e.g. here!
Like Juerg appears to assert, I fear that this is very much the risk!

Solutions?
Like I said, maybe it's not that difficult.

• Research and data per se are neither bad nor good; and if the track record is any indication, nobody is going to ever be able to stop scientific progress whatever the associated risks. That's just how things roll in science.


• But the risks are real - re-read the examples in Nature.


• Hence the inevitable conclusion, that whoever conducts the research cannot just disassociate himself from the possible consequences. Instead, it behooves the researchers to be fully accountable for their actions, and to be instrumental in mitigating the potentially negative implications of their queries. Obviously, this is easier said then done - but shying away from one's ultimate responsibility won't do, either!

But to come back to the topic of this post.
The data derived from telemetry studies (nice synopsis here!) are vital - but posting those tracks can only happen, if at all, with the utmost of circumspection.
It's exactly like in the case of Fish spawning aggregations where the ichthyologists have learned the hard way that it is better not to publish the exact locations: I say, unless there is unequivocal, robust and above all, fully enforced local management and/or protection, those data should be withheld and only shared with the relevant authorities and like-minded researchers, and this only in the aim of enacting adequate conservation and management measures.
And even once those measures have been enacted, it should be amply sufficient to publish large scale maps and keep the fine scale and exact GPS coordinates a secret.

Or am I missing something here?