Pike Country Weathermen

Pressure-Sensing Fish Can fish sense changes in atmospheric pressure? A recent study showed that movement of blacktip sharks was triggered by a drop in barometric pressure associated with Hurricane Gabrielle in 2001. Researchers with the Mote Marine Laboratory in Sarasota, Florida, report that the juvenile sharks responded to the approach of the storm by moving to deeper water, returning to shallow water after the storm’s passage. That study prompted the research being carried out by marine biology Ph.D. student Lauren Smith at the University of Aberdeen in Scotland. She’s studying pressure-sensing abilities of sharks in the wild, as well as through the use of an altitude chamber, which can mimic changes caused by weather fronts. Prior research by her supervisor, Dr. Peter Fraser, shows that sharks sense pressure using hair cells in their vestibular (balance) system. To learn more about how atmospheric pressure affects fish, Smith recommends the book Trout, Salmon, and the Evening Rise: The Barometric Breakthrough by Andrew Betts (publ. Salar Pursuits). “It provides a summary of research into pressure detection in fish,” she says. “In general terms fish with swim bladders, like pike, are able to detect pressure changes at a threshold of 0.05 millibars, while fish without swim bladders, such as sharks, have a higher but still sensitive threshold of 0.5 millibars. Physiologically speaking, there’s no reason why fish cannot detect barometric pressure changes.” (The millibar is a metric unit of atmospheric pressure; standard atmospheric pressure is about 1,013 mb at sea level). Smith explains how pressure changes in the atmosphere relate to water pressure and fish. “Say for example the air pressure rises from 1,009 to 1,010 millibars. The water pressure—the hydrostatic pressure—changes accordingly and acts as a transducer, relaying this information to the fish by having a direct effect on the swim bladder. If the air pressure remains the same, fish will be neutrally buoyant in the water column and thus able to maintain a constant depth. Increases in air pressure can cause the swim bladder to compress, so the volume of air in the fish is less, the water displaced by the fish is also less, and the fish begins to sink. “This may explain why fish with open swim bladders, like salmon and trout, come to the surface to gulp more air during increasing barometric pressure—they need to increase the volume of air in the swim bladder to become neutrally buoyant in the water column. The pike has a closed swim bladder and changes its volume of air internally.” Can dropping pressure stimulate pike to feed more actively? “Lower pressure has the opposite effect of rising air pressure, in that swim bladder volume will increase and cause the fish to rise in the water column,” Smith explains. “One hypothesis is that falling pressure causes smaller fish to become active, attracting predators such as the pike. Perhaps pike respond to an interaction of barometric pressure change, both directly on its own swim bladder and indirectly through prey response.”

“That may very well be the reason wind is beneficial,” Pyzer says. “Waves act to break up the water surface pane, limiting the amount of sunlight that’s transmitted through it. In summer, I target big pike in deeper water, an ideal spot being 15 to 25 feet deep around rock humps. But put a wind onto the shoals and the pike move up on them en masse. The wind drives them, creating the ideal light and temperature conditions. I suspect the same light effects occur when rain fronts and storms are approaching. Cloud cover increases, which reduces light intensity to levels that Casselman shows can activate pike into a feeding mode.”

Response Patterns

“Weather definitely affects pike,” says In-Fisherman Editor Matt Straw. “This time of year, the fishing can be good when a longterm rainy front parks itself for a while and brings consistent winds. Even shorter-lived rains and storms can turn fish on.”

Straw recalls a trip to Nueltin Lake: “This lake’s way up north on the Manitoba-Nunavut border, so the fish stay on a shallower weed pattern all summer. We were catching fish, and then a storm started billowing in over the trees. The skies darkened and we began to catch pike after pike, until the bottom dropped out and we had to stop fishing. When we went back out we had sunny skies and cold-front conditions, and the pike were so inactive we had to use our fishing rods to roust them out of the weeds to get them moving.

“I focus on three main patterns for pike during late summer,” Straw says, ”and depending on what a lake offers, you might have one or more of these patterns to work with. If water temperatures are cool enough, you can find big pike on weedlines. If the water’s too warm shallower, they can be out suspended in deeper open water, or positioned closer to bottom on deeper structure.

“If it’s flat, calm, and sunny, suspended fish and weed fish get tough. The odds-on call is to target structure from 20 to 40 feet deep, but they can be as deep as 60 feet. That’s when I bring out the snap-jigging routine. Find big areas of bait on sonar and pike should be there. I like to use a 1- to 1.5-ounce jig, like an Esox Cobra Head, but any standard bullet or football head works,” he says. “Match it with a 7- to 8-inch plastic like a Bait Rigs Reaper or Mann’s Jelly-Hoo. The Berkley Gulp! Eel is another one to try. Get to bottom fast and hit it hard, snapping the jig off the bottom by 6 feet or more. A 7- to 7.5-foot heavy flippin’ stick with 20- to 30-pound braid is a good setup for this.”

When cold fronts bring a tough bite, PWT Executive Director Jim Kalkofen focuses on deep, main-lake points in the lakes he fishes across Minnesota and Wisconsin. “If there’s deep cabbage available, it makes for an ideal point,” he says. Kalkofen’s program utilizes a combination of crankbait and jigging tactics to work deeper areas off points in depths ranging from about 15 to 30 feet.

“My favorite cold-front crank for pike was the big Rapala Risto Rap, sending it to bottom and bumping it off rocks. Other good baits are the Bagley DB06, Yo-Zuri Crystal Minnow Deep Diver, and Rapala Tail Dancer Deep. Run them near bottom, and also try cranks that work mid-depth zones for suspended fish. Long casts are best to get baits down to their effective working depths. Trolling is another good option.