July 1951 COMMERCIAL FISHERIES REVIEW 17 



beginning this year's exploration, the operations of the vessel have been seriously 

 hampered by strong northerly winds from 30 to 50 miles per hour which prevailed off 

 the Northwest coast. Conventional trolling gear failed to take any albacore by 

 July 14 when the gill-net catch was made. 



For the first two weeks in July, the vessel fished off Oregon in waters with 

 surface temperatures between 58° and 60° F., but because of the strong winds, fish- 

 ing efforts were mostly restricted to unsuccessful surface trolling with jigs. Gill 

 nets and long lines will be tested extensively as soon as the weather permits. 



The John N. Cobb was engaged on a similar exploration in the 1950 season, and 

 last year caught the first tuna on June 18, approximately 480 miles west of Cape 

 Blanco, Oregon. 



Ship Worms Being Studied by Maryland Biologists 



Ship worms, long bivalve mollusks that cause great destruction by boring into 

 timbers of wharves and hulls of wooden ships, are being scrutinized carefully by 

 biologists at the Maryland Department of Research and Education at Solomons. 



Investigations to determine at which times larval ship worms, which are free- 

 living and not settled like their parents, attach themselves to bottoms of ships 

 and other objects are being conducted by the Director of the Chesapeake Biological 

 Laboratory. If more information is known about this phase of ship-wonn life, boat 

 owners can be warned when to remove their boats from the water, or when to paint 

 them with antifouling paints to prevent attack. 



In addition to ascertaining the seasonal activity of ship worms, Dr. R. V. 

 Truitt, the Director, is determining: 



1. Kinds found in Chesapeake Bay; 



2. Rate of growth of each important species; 



3. ^Afhere they strike in regard to the salinity and 



depth of the water. 



The shells of ship worms are about one-half inch long, but the soft parts of 

 the body outside the shell may be from six to twelve inches . l-Jhen full grown, a 

 ship worm occupies the tunnel it has excavated in timber, lining it with a shelly 

 substance. One female ship woiro can produce millions of eggs, from which the micro- 

 scopic free-swimming larvae are hatched. After a week or two, when the larva is 

 about the size of a pinhead, it settles on the surface of a submerged timber and 

 bores a tiny hole just large enough to admit its body. Thereafter, it continues 

 to bore, enlarging the hole as its body grows in length and diameter, keeping in 

 contact with the outside of its tunnel by means of its delicate, threadlike siphon. 



The ship woim's method of tunneling into timbers is almost entirely a chemical 

 process. The Director declared that "Wood is practically digested away from the 

 point at which the worm burrows. This is accomplished by the action of an enzyme 

 or soluble ferment that splits cellulose, the basic material in the makeup of wood 

 structure, into material that can be partially digested. Actually, ship worms have 

 no teeth, screwdriver-like borers, or other devices for drilling or piercing wood." 



