Wednesday, February 5, 2014

Seafood Business Locked in the Throes of Winter

Here's an insight to what is going on with our native striped bass, aka rockfish, during these cold winter months.  Tim Sughrue posted this and I thought it would be an interesting read for those of you who look at those frozen waters and wonder what's going on underneath.  Tim is a fisheries scientist and works for Congressional Seafood.  

"I drove across the Bay Bridge last Thursday on my way to the fish market, as I have every
day for the last 30 years, and saw a sight I have only seen once in my life, in 1977. The Bay was completely frozen all the way across (Kent Island to Annapolis-5 miles) and as far north as you could see. From the top of the bridge, I could see Pooles Island off the mouth of the Middle River, 20 miles to the north, and the Bay was a huge sheet of continuous white ice all the way up. From there, it is another 20 miles to the top of the Bay at Havre De Grace, where the Susquehanna comes in, the water is fresher (less salt) and the Bay is narrower, lending itself to freezing across more readily. So last Thursday morning, when my truck thermometer said 1 below zero, 20 percent of the largest estuary in the US, the Chesapeake Bay, was frozen all the way across for 40 miles. It was quite a sight.

Cold winters are not all bad. Historically, they have been quite good for rockfish reproduction in the spring. The ice and snow hold back the nutrient runoff. The water temperatures are lower, delaying the first algal blooms until mid-March, exactly when the fish are spawning. Algae, phytoplankton and zooplankton are the primary food source for the rockfish larvae, the life cycle stage between egg and fingerling. The increased food supply for the rockfish larvae results in a higher survivability for that stage, and a much larger year class of fingerling rockfish. God knows we need one. We have had only one dominant year class in the last decade, 2011. The population of the adult jumbo rockfish (migratory) has plummeted. Our resident population in the bay is doing fine. Fishing, both recreational and commercial, should be excellent this summer as the 2011-year class will be of legal size (18 inches). You can expect the federal overseer of the striped bass fishery, Atlantic States Marine Fisheries Council, to drastically change how the coastal states (Massachusetts to North Carolina) fish for adult striped bass in their waters.

The ice on the Chesapeake Bay makes it extremely difficult for the watermen to get out and work. For the ones who are able to break out, it is also very dangerous. The force generated by large sheets of ice, moving with tide and wind, can bend wheels, break struts, and even crush hulls. Working on the water in the winter is not for the inexperienced.

For the watermen participating in the drift gill net rockfish IFQ now, ice on the Bay means the rock are easier to catch. For the ones who are able to get out, the rockfish are lethargic, and sitting in tight schools right on the bottom. The fishermen find the schools of rock deep in the channel on their depth finders, lay off their nets at the end of a tide, when the water slows. Drift nets only fish the bottom 10 feet of the water column. So if the fish are in 100 feet of water, as they frequently are this time of year, the net only catches fish if they are very close (90-100) to the bottom. Fish have a natural defense against nets. It is called their lateral line system. This is a line you can see that goes right down the middle of the fish lengthwise.  The lateral line has hair follicles in pores that sense changes in the current ahead of the fish. This system allows fish to catch prey and navigate even when they cannot see. But at the end of the tide, there is little current movement and the fish are vulnerable to the nets. When the tide is “running”, the fish can “feel” the change in the current ahead of them and simply swim around or up and over the net. Fishing with a gill net is much like hook and line, if the conditions aren’t right, you are not going to catch much."

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