BY: Charles R. “Bob” Hitz Sept. 16, 2012
As a novice fisheries biologist on the deck of the R/V John N. Cobb I saw an unbelievable sight that will remain with me forever. It was when haul # 20 was retrieved after the trawl had skimmed along the ocean bottom, 125 to 140 fathoms below the surface.
I had recently been hired by the Exploratory and Gear Research Base in Seattle and was on one of their exploratory cruises along the Oregon coast in May 1961(1). One of our objectives was to explore the deep water along the top of the continental slope. Navigation charts show the 100 fathom (600 feet) contour, which is the dividing line between the shallower shelf and the deeper slope.
We had delineated two possible trawling grounds in this depth interval along the west side of Heceta Bank. The southern ground was directly west and the northern one was more to northwest. We started the sampling process by setting the gear on the northern ground using an eastern trawl, which was our standard fishing equipment.
After an hour of towing the net along the bottom, haul #20 was retrieved. I was looking aft when the trawl doors reached the vessel, anticipating the cod end would float up to the surface to reveal the catch. Instead, the ocean behind the vessel erupted violently as a huge ball broke the surface and rose 8 to 10 feet in the air as sheets of water cascaded off it. It happened so quickly I couldn’t believe my eyes. The net was full of Pacific Ocean Perch (POP) and their air bladders had expanded as they were brought up from over 100 fathoms of water, forming the cod end into an enormous ball. The air bladder in a rockfish is a device that controls its equilibrium at depth, similar to a submarine’s method of taking on water to sink and forcing it out with compressed air to rise. The fish’s air bladder adjusts internally, so once the fish are netted and raised rapidly through the water column with no opening to let the air out, the bladders expand like a balloon.
The catch was brought aboard in 5 splits (2,000 lbs. each) and a lift, which brought the total catch to 11,765 lbs, almost 6 tons of fish. The dominant species was POP, which accounted for almost 94 percent of the catch or 11,000 pounds. There were also 350 lbs of other rockfish that were classed as red rockfish, and 125 lbs of black rockfish. These were separated and identified to species using my draft of a field key. The rest of the catch consisted of sablefish, hake, Dover sole, Rex sole and turbot.
POP appears to be the most abundant of the 55 species of rockfish found along the Pacific coast. In those days we believed they were fast growing and we didn’t know much about their reproductive cycles, although we did know they were all ovoviviparous. Their eggs are fertilized internally and they carry their young until they hatch and are released as larva into the oceans, where they fend for themselves. We also knew that POP release their young in the winter.
When the catch came aboard and was sorted, we took a subsample of the POP and each individual was opened up to determine the sex as well as the maturity of the females. Then each was measured for total length. Otoliths or ear bones, about half an inch in length, were taken from certain fish by cutting the top of the neck just behind the head and bending it down to expose two otoliths, then picking each out with tweezers and putting them into an envelope, identifying them to individual fish. They would be given to a biologist who specialized in ageing fish. I was interested in the maturity of the females and found all the POP to be in a transitional stage of maturity in May, which would coincide with past findings of their releasing their young in the winter. I was in heaven, working on deck looking at a virgin resource that had hardly been touched or even known about throughout time.
The scientific staff was rotated in the middle of the cruise and the vessel returned to continue the last half. One of the objectives in the second part was to aid the Oregon biologists in their tagging program, and many of the tows were reduced to 20 minutes on the bottom so the fish had a better chance of surviving after being tagged. This was one of the first times rockfish taken from the deeper water were tagged. Once they were caught the best were tagged and the air bladder punctured, releasing the trapped air so they could sink back to the bottom and, hopefully, heal and survive.
Two weeks later in about the same spot on the northern grounds where the 11,000 pounds of POP were taken, the Cobb made haul # 41along the 111-109 fathom contour. After only 20 minutes on the bottom the gear was retrieved, and again the ocean exploded with the net rising out and literally blowing apart, leaving POP floating on the surface of the ocean. The catch was estimated at 40,000 lbs or 20 tons of fish, the largest catch that the Cobb had made.
The chief scientist on the second half of the cruise had visited many commercial trawl fishermen beforehand to determine where the exploration should be conducted. Afterward he called a number of trawlers in the area to let them know of the POP catches the Cobb had just made, and it was then referred to as the “PERCH SPOT”!
(1) Hitz, C.R. and D.L. Alverson, 1963, Bottom Fish Survey off the Oregon Coast, April-June 1961. Commercial Fisheries Review, June 1963 Vol. 25, No.6, Washington D. C.