Northwest Fisheries Science Center

The Main Deck

Acoustic and trawl adventures in the Northeast Pacific

This portal tracks the research and sea-going activities of the Fisheries Engineering and Acoustic Technologies (FEAT) Team from NOAA¿s Northwest Fisheries Science Center.  Follow us as we use acoustics, trawling, and oceanographic sampling to learn about the Northeast Pacific Ocean.

Back deck of Bell M. Shimada
Acoustic echogram of hake
trawl catch
 

Are they spawning?

By Sandy Parker-Stetter
January 30, 2016


Early on, we referred to this survey as the “Spawning Hake Survey” and said we were looking for spawning hake. Over time, we shifted to calling it the “Winter Hake Survey” and talked about looking for adult hake. Let’s talk about hake biology and what it means for the survey, and its name.

In the summer, Pacific hake are spread between southern California and Alaska or British Columbia. In the fall, they move southward and aggregate for spawning. Where they go, the size of the spawning area, and the size(s) of the aggregation(s) are not well understood. 

Over the fall and early-winter, the gonads of male and female adult Pacific hake (those that are older than age-2) develop gradually. After some time, their gonads are fully developed and the fish are ready to spawn. How long they can stay ready-to-spawn isn’t known. At some point, the hake release their sperm and eggs into the water and they are, technically speaking, spawning at that time. How this timing works, and how long spawning lasts, isn’t clear.

Saying that we’re looking for “spawning hake” sounds like we’re hoping to catch them in the act of releasing eggs and sperm. If we step back to the original survey goals, we’re not specifically interested in the act of spawning itself, although biologically that’s the important part. 

Instead, we’re more interested in finding the winter aggregations of adults regardless of whether they are preparing to spawn, are spawning, or have recently spawned. We want to know if they are all found in one giant aggregation, if males and females are in the same aggregation, and whether spawning occurs in a smaller geographic area than in summer. Shifting our language to say that we’re looking for adult hake during their spawning period is more consistent with what we’re trying to learn.

To tie this back to the survey and what we’ve found so far – we have found hake with developing gonads (pre-spawn) and some that are fully developed and ready-to-spawn. We have not yet caught any aggregations in the act of spawning, or found any fish that have already spawned (spent or post-spawn).  The search continues.

Female hake who isn’t ready to spawn.  Photo credit Pete Frey (NWFSC)

Female hake who is ready to spawn.  Photo credit Sandy Parker-Stetter (NWFSC)

Male hake who is ready to spawn.  Photo credit: Sandy Parker-Stetter (NWFSC)

Tagged: Winter hake survey

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