Northwest Fisheries Science Center

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Blog on ocean conditions along the Newport Line and the northern CA Current.

Pelagic Fishing Not So Hot

By Ric Brodeur
June 22, 2016

Pelagic juvenile rockfishes.

We are one week into our survey now and have been progressing steadily northward.  Although there have been little tidbits in the previous reports about the fishing, I have to say that it has been less than exciting so far with the catches.  As background, we generally do four midwater trawls an evening with a modified Cobb trawl with a fine-mesh liner.  It is towed with the headrope at 30 m and has about a 10 m vertical opening so we are fishing a distinct layer which we expect the juvenile rockfish to be.  We could physically do more than 4 tows a day but these tows need to be done when it is completely dark out but unfortunately we are around the longest daylight of the year and moving further north so the amount of time we have to work in is limited.

A 38 kHz acoustic image collected during the Tillamook Line transect during a tow. 
Note the darker green/yellow layers near the surface (top of screen) which are likely juvenile hake.

So what do we catch?  Compared to previous years (even last year’s Warm Blob sampling), the catches have been very low.  We have caught our main target species, juvenile rockfish, in less than half the tows.  Last night was the first time we caught them at all four stations but the catch was very low.  Catches of our other target species (young-of-the-year (YOY) Pacific hake and flatfishes) had been fairly low but we did finally get some big catches of YOY hake (50-60 mm) yesterday at our two far offshore stations (>1000 and >10,000 per haul) along the Tillamook Line.  The larger catch was associated with a dense layer in the upper 50 m of the water column that was giving off a strong acoustic signal at 38 kHz (see picture).  Even the normal mesopelagic species such as lanternfishes and small squids seem to be in lower abundance compared to other years.  The only taxa that appear to be increasing is the offshore gelatinous group called pyrosomes.  In the past, we hardly got these at all but their abundance started increasing during the Warm Blob last year, but this year it seems to be the highest catch in terms of biomass overall. 

Medusafish (Icichthys lockingtoni) on top and ragfish (Icosteus aenigmaticus) caught in the same trawl.

We have been scratching our heads trying to figure out what is happening here.  We have been getting reports from other vessels (e.g. Ocean Starr) that they are getting larger than normal catches of YOY rockfishes this year.  However, they are using a much bigger net, sampling at the surface, sampling during the daytime, and perhaps most importantly sampling much closer to shore.  We suspect that the rockfish are in the more productive nearshore coastal zone and avoiding the low productivity offshore waters, unlike previous years.  The big catches have occurred off the coast of Washington whereas we have been working off of Oregon which may be less productive this year. The differences may be due to El Niño and the strange weather patterns we are seeing (almost no upwelling favorable winds) so far.  We would like to move closer to shore but we are a bit more restricted for fishing in shallow waters.  We also want to at least repeat the same stations that we have sampled the last four surveys to facilitate inter-annual comparisons. However, when we finish our regular sampling we hope to do some experimental tows as close to the shore as we can get and also towing the net at different depths in the water column. 

Juvenile king-of-the-salmon (Trachipterus altivelus) caught in trawl.

The small catches of target species aside, we have caught some interesting taxa including a ragfish and several medusaefish (both of which are likely commensal with large jellyfish) and a large king-of-the-salmon (see pictures).  We’ve also collected a variety of invertebrates at most stations including many gelatinous critters, some of which we have not been able to identify with any certainty.  We will see how the catch changes tonight as we are now north of the Columbia River off Willapa Bay, Washington.

Tagged: Prerecruit

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