This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
Editor's Note: Marine biologist William Gilly is on an expedition to study Humboldt squid on the University-National Oceanographic Laboratory System research vessel New Horizon in the Gulf of California. He and other scientists are learning about the giant squid, their biology and ecology on this National Science Foundation-funded expedition. This is his fourth blog post about the trip.
GULF OF CALIFORNIA—Days 5-7 Bahia San Rafael: When looking for squid or fish or anything that is hidden beneath the surface of the sea, it is often helpful to search not for the animals themselves but for the commercial fishermen who know where they are. Because the livelihood of their family (or even of a whole town like Santa Rosalia) depends on reliably locating the targeted species, a good fisherman will know a lot about the relevant ecology—depth preferences, day-night movement patterns (both vertical and horizontal), diet, size-dependent differences and a host of other important factors. Tapping into this informal knowledge base has really helped our program of Humboldt squid research over the last decade. In fact, we have specifically designed tagging experiments to confirm what fishermen reported to us, and generally the data collected turn out to be consistent with their hypotheses. By following this approach, you can save a lot of time and money. Admittedly, the hypothesis tested tends to be locally focused, but that is an important start to putting together a larger picture.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
So it was with glad eyes that I spotted a dozen steel fishing vessels anchored along the north end of Bahia San Rafael after we emerged from the fog bank. These guys would not be here in this number if there were no big squid. We expected them to head out to the fishing grounds at sunset, so until then we carried out an acoustic survey searching the area ourselves. At sunset the boats turned on their deck lights and all headed out to the general area of the 300 meters shelf break in the channel, much as they would do if they were fishing in Santa Rosalia.
Although these boats are all rigged for shrimp trawling, that season is now closed, so they are here fishing squid—with hand-lines and jigs, not with nets (they are illegal in Mexico). But these are not the small pangas that typically fish out of Santa Rosalia. Most of the boats here are from Guaymas and fish for several days at a time, only because they lack refrigeration. One larger boat from Mazatlan has ample freezing capacity and will be here for 40 days. There are no pangas operating here, because we are at least 25 miles from the nearest paved road at Bahia Los Angeles to the north, and the small pangas must unload their catch every night to a truck waiting to transport it to where it can be processed (Santa Rosalia or Ensenada?). Fishermen in Santa Rosalia told us that some pangas were taken by truck to Bahia Los Angeles for the fishing, but they are far from this spot.
It is interesting how quickly the fishing effort can change location—it may be as adaptable as its quarry. Historically, squid fishing in the Gulf has been fairly well limited to the Guaymas and Santa Rosalia areas, because there are a lot of squid close to processing and transportation capabilities. But our research in other areas over the last five years has turned up several sites that appear to regularly host large populations of squid and are off the beaten track. These spots may be too distant for the panga fishermen to safely or economically utilize. But these larger vessels, as decrepit as some appear to be, are not so limited by distance from shore. So when the squid abandon their usual haunts, the artisanal panga fishery suffers most. If they are lucky, these fishermen can haul their pangas elsewhere to fish, but if the squid move far offshore or to a remote part of coast (or into the open Pacific ocean), that is not an option. I wonder what is happening in Bahia Los Angeles and how may panga fishermen from Santa Rosalia are there—and how many are not, waiting at home for the squid to return.
If you independently hear the same "fact" from three fishermen, you can tend to believe it. So we approached within a few miles of the fishing fleet as darkness settled and began our own jigging session. It was not long before we found what we have been searching for the past week —big Humboldt squid—both on our jigging lines and on the sonar display. We sampled 21 big squid, from about 50 centimeters to 80 centimeters body length, and about half (the larger ones) were fully mature. The others were quite immature. But even the smallest of these squid was almost twice the length of the largest squid we had sampled near Isla Tortuga at the start of our quest, and many of those small squid had been fully mature. So these large squid seem to fit the "normal" pattern for the Guaymas Basin—small squid are not mature. But what about small squid here in jumbo? Indeed, a quick sampling of eight small squid (20-30 centimeters length) showed that they were all very immature.
A quick sample of small squid brings up another topic that I have been pondering. I have wanted to work on small Humboldt squid for behavioral and neurophysiological experiments for the last decade, but it has heretofore been problematic finding small squid. And if you are lucky enough to find small squid, it is not always so easy to catch them. A 10-inch squid typically does not attack the 16-inch giant jigs used for big squid. The El Nino-like winter appears to have solved the first problem—there are small squid everywhere. But catching them proved to be another thing. My first attempts on this trip were fruitless, but I was soon guided by Pete, a crew member who worked for over a decade on an overnight sport-fishing boat out of San Diego. Well, actually I casually observed what Pete was doing, because he was catching a lot of small squid. The technique was brilliant in its simplicity. He simply cast a small, unweighted jig on light line and let it slowly flutter down as it was swept along in whatever current the wind and sea dealt up. With your finger tips on the loose line you can feel the most gentle of tugs, and you do need to feel the tugs to snag the squid. It is rather like fly-fishing for squid, and its beautiful simplicity makes it work anywhere. Use the current and wind to work for you—don’t fight them and wish you could control nature. That lesson is as old as life, but we so often forget.
Again, absorbing practical, local knowledge into scientific methods and research can pay off enormously. Obviously even the most fanatic purist scientist wouldn't go about trying to catch small squid in an unfamiliar place by systematically varying the type of jig, strength of line, limberness of rod, depth at which to fish, type of action to give the jig, position on the vessel, and a hundred other variables. Of course, if they did they could statistically predict what the best way to catch small squid would be. That might or might not have any relevance at the next jigging stop.
My experience with Pete has been replayed in a variety of ways with many of the crew. They are incredibly knowledgeable and represent a vast and deep human resource. They are happy to share and teach if you ask. Perhaps NSF should host a chat-room on its web site that would allow posting questions that the crew might be interested in: "I will be on the New Horizon in June—how can I catch small squid, or juvenile flying fish, or…?" It only takes one good answer to make your day. Again, it’s all about saving time and money—and you might just make a good friend in the process.
Image of quid boats at anchor courtesy of Capt. D. Murline; image of lighted squid boat at dusk courtesy of Capt. D. Murline; image of big Humboldt squid courtesy of R. Rosa; image of fisherman Pete in search of big squid courtesy of Capt. D. Murline