LOUGH: LARVAL DYNAMICS OF DUNGENESS CRAB 



NHIO 



J ' j'aIs'o'n'd|j'f'm'a'm'j'j'a's'o'n'd|j'fIm'a'm'j'jIa ' 

 1969 1970 1971 



FIGURE 2.— Surface salinity (Z.) at stations NHOl, NH03, NH05, 

 and NHIO from June 1969 through August 1971. 



TABLE 1. — Location of plankton sampling stations and bottom 

 depths along the Newport Hydrographic line (NH) off Newport, 

 Oreg. 



Station 

 (Lat. 44'39.1'N) 



Long. 



Depth 

 (m) 



20 



46 



59 



85 



95 



142 



330 



220 



340 



1,060 



1,300 



2,850 



coast. Plankton samples initially were collected 

 at the four inshore stations (NHOI-NHIO) con- 

 stituting the main series of samples from June 

 1969 through August 1971. The sampling pro- 



gram was extended offshore to NH60 by 5- or 10- 

 mile intervals beginning with the 3 February 

 1971 cruise. 



A high-speed bongo net sampler (Posgay et al. 

 1968) with a 0.2-m mouth diameter was used ex- 

 clusively from 22 June 1969 through 20 October 

 1970. The two cylinder-cone nets, 1.8 m in length, 

 were constructed of 0.233- and 0.571-mm nylon 

 mesh and had an effective straining surface (pore 

 size area) to mouth area ratio of ca. 10 to 1. A 

 30-pound lead ball or a 15-pound V-fin depressor 

 was attached to the sampler line. 



Starting with the 4 November 1970 cruise, a 

 0.7-m diameter bongo net sampler was used in 

 conjunction with the 0.2-m sampler to strain a 

 greater volume of water and to reduce avoidance 

 by the larger larvae. The 0.7-m bongo nets had a 

 net length of 5.1 m, were constructed of 0.571-mm 

 nylon mesh, and had an effective straining area 

 ratio of ca. 8 to 1. Both samplers were equipped 

 with TSK^ flowmeters mounted on brackets 18 

 cm from the rim of the inside frame. A multiplane 

 kite-otter wire depressor (ca. 80 pounds), modified 

 after Colton ( 1959), was used with the dual bongo 

 net array to produce a wire angle ratio of 2 to 1. 

 The sampling objective was to make a high speed, 

 oblique, plankton tow, sampling the water col- 

 umn in equal stepped intervals from 150 m depth, 

 or in shallower areas from bottom to surface. 

 Wire was let out and retrieved at 50-75 m/min 

 while the vessel was underway at 2-3 knots. Most 

 of the samples represent daylight (0600-1800) 

 tows ranging in duration from 10 to 25 min. The 

 longer tows were generally made on stations 

 beyond 5 miles. Plankton samples were im- 

 mediately preserved in 5-109'f Formalin and later 

 buffered with sodium borate. 



A bathythermograph (BT) cast was made at 

 each station near bottom or to 150 m depth. Sur- 

 face bucket temperatures also were taken at each 

 station to calibrate the BT readings. Salinity 

 samples were collected on the surface and near 

 bottom or to 150 m depth by a Nansen bottle cast 

 and analyzed by an inductive salinometer. Salin- 

 ity, temperature, and depth (STD) data from a 

 real-time printout computer were available for 

 several cruises. 



The Nekton Cruise of 11-12 April 1970 at sta- 

 tion NH45 was included in this study as it is one 

 of the few cruises that sampled the offshore 



^Tsurumi-Seiki Kosakusho. Reference to trade names does 

 not imply endorsement by the National Marine Fisheries Ser- 

 vice, NOAA. 



355 



