922 



Fishery Bulletin 97(4), 1999 



the inshore station (Figs. 2 and 3). All MESSHAI tows 

 were stepped oblique hauls. In the shallow tows the 

 sampler was lowered to 50 m and retrieved through 

 five 10-m strata, each in 2.5-m steps lasting two min- 

 utes, with a total of five horizontal phases per stra- 

 tum. Depth, temperature, and flowmeter profiles 

 were recorded by the deck unit throughout each tow. 



I-Mar 19^Mar 20H hMar 23-4-Mar 24-|-Mar 25H hMar 27^ 



» 30 



^Mar 19 + Mar 20^ hMar 23+Mar 24-|-Mar 25H hMar 27 H 



160 - 



200 - 



Figure 2 



Diagram showing chronology of MESSHAI tows, depth strata sampled, and 

 isotherm.s for the offshore station ifrom Pommeranz and Moser, 1987). i Above i 

 Shallow (50 m) and Manta tows; the dots represent average depths for each 

 net; the seven complete vertical lines show when deep i200 m) tows were taken. 

 Tow numbers for Manta tows are" given above solid triangles and tow numbers 

 for MESSHAI tows are given at the bottom of each series of vertical lines. Iso- 

 therms are shown in 0.5 C intervals. (Below) Deep tows; the 17 lines extend- 

 ing down to 50 m indicate when shallow tows were taken. Isotherms are shown 

 in 1 C intervals. 



Bucket surface temperatures were taken periodically 

 to calibrate the MESSHAI temperature sensor. In 

 the deep tows the sampler was lowered to 200 m and 

 retrieved through five 40-m strata, each in five steps 

 lasting two minutes. The total number of successful 

 MESSHAI tows was 24 (shallow: 9 day and 8 night; 

 deep; 4 day and 3 night) at the offshore station and 

 36 (shallow: 12 day and 12 night; 

 deep: 6 day and 6 night) at the in- 

 shore station. Improper preserva- 

 tion or breakage resulted in the loss 

 of anchovy eggs in net 4 (20-30 m 

 stratum) of tow 42 and the entire 

 sample from net 3 (30-40 m stra- 

 tum) of tow 61. Three MESSHAI 

 tows were unsuccessful owing to 

 technical difficulties, and the 

 samples were subsequently dis- 

 carded. All tows were made at a ship 

 speed of -1.5 knots. Before each net 

 tow series at the inshore station, a 

 pump and fluorometry system 

 (Lasker, 1978) was used to obtain a 

 chlorophyll profile down to 40 m 

 depth. Water samples were taken at 

 the surface and at the chlorophyll 

 maximum for chlorophyll-a and 

 phaeophytin extraction and fluoro- 

 metry, and for identification and 

 counts of major phytoplankton taxa 

 (analyses not included in this pa- 

 per). Oblique bongo net samples 

 were taken at each station at a ship 

 speed of about 1.5 knots; except for 

 length-frequency information, data 

 from these tows are not addressed 

 in this paper. 



Most samples were preserved in 

 S'^ buffered formalin; selected 

 samples were preserved in 80% 

 ethyl alcohol for analysis of otolith 

 daily growth rings in anchovy lar- 

 vae. Prior to sorting, wet zooplank- 

 ton displacement volume of each 

 sample was measured using stan- 

 dard techniques (Kramer et al., 

 1972). Anchovy larvae and eggs 

 were identified and removed during 

 the plankton sorting process; eggs 

 were classified by stage according to 

 the criteria of Moser and Ahlstrom 

 ( 1985 ) and length measurements of 

 larvae were taken to the nearest 

 0.5 mm. Larvae of other fish were 

 identified to the lowest taxon possible 



