If you’re a tuna fisherman with a yen to know more about the fish you chase and catch, here’s a new book, “Tuna Smart,” that will add a bunch to what you already know.The five species of eastern Pacific tuna, and particularly yellowfin tuna, have been studied by scientists interested in preserving the stocks, or what might be called a viable biomass. Much of what has been learned can benefit anglers who pursue this great game fish, but little of it has been available that’s understandable by the layman, the everyday saltwater angler.
USC scientist Robert Douglas of Ranch Palos Verdes is a fisherman who loves catching tuna. That’s author Bob in the photo with a “cow,” or yellowfin tuna over 200 pounds.
Douglas has done some deep diving into the accumulated science on yellowfin and the other tuna, and what he’s found and published in his new book will help novices and salty captains alike. I learned at least a dozen new things about tuna and their habits in a couple of hours with this handsome little book.Plenty of charts and graphs illustrate the facts and observations. Bob talks about things like “bounce diving,” and explains what it is and how it works for tuna on page 53. The “bounce” is from the surface to the deeps and back, and it’s part of the tuna daily routine. The fish go up and down, seeking food and comfortable temperatures. Well-known San Diego scientist Kurt Schaefer provided some of the visuals for the section.
All tuna practice bounce diving, says Douglas, but yellowfin and skipjack do it the most, and bigeye go deepest. Another table shows averaged yellowfin growth: 12 pounds after the first year, 23 after the second, 36 following the third and 48 pounds for a four-year-old tuna. These numbers show what anglers have believed for a long time.
Like fisherman, scientists are interested in the relationship between tuna and the species they eat. Figure 57 on page 96 has a table that illustrates the abundance of sardines and anchovies. When one species is prevalent the other appears to decline. There’s a fairly complex relationship between tuna and their prey species, and it has to do with factors like the California Current and El Nino, with upwellings and surface temperatures influencing the “boom or bust” populations of baitfish.
Catches over the years and the Pacific Decadal Oscillation (PDO) are measured in the Douglas book, another relationship that has influence on what kind of tuna we see near the west coast, and how many show up to offer targets for anglers.
How these fish swim, breathe, eat and reproduce has much to do with catching them. The knowledgeable angler will likely be advantaged in many situations. Hey, anybody can catch ‘em when tuna are so frenzied they’re biting a rod’s length from the boat! Bob also notes the increased range of the Humboldt squid that sometimes plague the west coast on page 102.
This is a book that helps bridge the gap between science and fishing. Like fishing (and science, too) it offers no promises to increase the number of fish in your bag or cooler, but if you read it with comprehension, it promises to increase your smarts. So get smart; get Tuna Smart!
Tuna Smart, by Robert C. Douglas, © 2015 The Swordfish Press, (Dr. Todd Larson) 4240 Minmor Drive, Cincinnati, OH 45217
Now Leading
This announcement comes from John Campbell, organizer of the Yellowtail Derby from May 21.
“A 45-pound White Seabass was landed at 5:45 P.M. Wednesday evening off Mission Beach. I just received the Weigh Slip. The angler is Josh Levine, who entered the Derby yesterday morning. Josh landed the fish on 50-pound test line, with a live mackerel for bait. He was fishing on a Kayak.”
