Pacific Herring Spawning


When Pacific herring spawn here in the San Francisco Bay, sea lions, seals, pelicans, and tens of thousands of cormorants, gulls, and migratory ducks are in a feeding frenzy. It occurs primarily in December and January.


The herring are known as a keystone species, a species that has a large and critical effect on the surrounding ecological environment.


A well-fed sea lion relaxing

If all the contingency factors are in place, in the late fall the Pacific herring come into the San Francisco Bay, especially Richardson Bay.


They wait for water temperature, salinity, and other conditions to be just right, then they head to the shallow shorelines to begin their reproductive process. Males release sperm, females release eggs.


She releases thousands of eggs at a time, up to 20,000.


Brown pelicans, Sausalito


The Pacific herring prefer a sea grass known as eelgrass (Zostera marina) for depositing their eggs and protecting their young. The eggs are adhesive, and are also sprayed onto rocks, pilings, and other underwater structures.ย  Eelgrass info here.


Gull with a piece of eel grass



Eelgrass, Zostera marina. Photo: Ronald C. Phillips, PhD. Courtesy Wikipedia.

A typical herring adult is about 4-8 inches long (10-20 cm). And being at the low end of the food chain, they have numerous predators, including humans. The juvenile survival rate is about one adult per 10,000 eggs.


It is easy to see when a “spawning event” is occurring. I’ve been watching them for weeks.ย  Although it’s impossible to see what’s going on underwater, above water there is a flurry of activity. I find the spectacle endlessly fascinating.


Gulls, cormorants, pelicans, ducks, and sea lions congregate near the shoreline. They eat the fish and the eggs. Sea lions are diving and snorting, thick flocks of birds are everywhere, there’s splashing and squawking.


Wikipedia Pacific herring.


Juvenile Pacific Herring. Courtesy Wikipedia.

After the eggs are released, the surviving embryos turn into larvae, then juvenile fish. In fall they swim out to sea, riding California currents.


There have been years when the herring were overfished; populations declined. Some years the herring population fell so low that fishing was prohibited. See graph at end.


When herring fishing had to be curtailed, people were forced to cooperate and manage the situation before the herring were forever lost. And they have.


Herring fisherman, conservationists, naturalists, scientists, and residents have joined together in an ongoing effort to host the herring. Dredging, boat activity, global warming, algae, oil spills and other pollution have all been important topics.

A raft of sea lions

Cormorants, Tiburon


Pacific Herring Management Plan, California Dept. of Fish & Wildlife.

Herring Field Staff at Work on the R/V Triakis, Photo Credit: Ryan Bartling

Herring Field Staff. Photo: Ryan Bartling. Courtesy

It is impressive to see what humans can do when they work together, and that spawning miracle is pretty amazing too.


Photo credit: Athena Alexander unless otherwise specified.

Global capture of Pacific herring in tons, 1950-2009. Research by Food & Agriculture Org., graph courtesy Wikipedia.



76 thoughts on “Pacific Herring Spawning

  1. What a sight! Glad I could see it through your camera. It’s a fish non-fry. ๐Ÿ™‚ I’m encouraged to read that everyone cooperated to bring back the herring. We need all the good news and examples of this sort that we can get. Cooperation isn’t much seen these days, anywhere and on any topic.


  2. Great post! This is one of nature’s little known, but great spectacles that I really want to see some day. There is an entire eco-system along the west coast of the North American continent that is driven by the salmon and herring run. Fascinating and still not fully understood.

    • You are right, David, there is still a lot that is unknown about the herring spawning. We may not know everything that precipitates it, but it sure is a marvel to witness. Thank you for your generous comment, much appreciated.

  3. A fascinating flurry indeed! What a thing to watch, full of active life (and death, sniff) as these wonders occur. Loved reading about this keystone species, and the cooperative efforts made to ensure survival – there’s hope for the planet yet!
    Thanks, Jet, and have a great weekend!

    • Always a joy to hear from you, pc, thank you for your comment. The frenzy of it all is spectacular, I am glad I could share it with you today. That we know about keystone species and set plans to conserve them really does point to hope for saving our planet. I hope you and Mrs. pc have a fun weekend with your new canine pal.

  4. Pingback: Pacific Herring Spawning โ€” Jet Eliot |

  5. Thanks for the glimpse into the seldom-seen underwater world of marine life.
    Most of us never take notice of major ecological events like fish spawning until wildlife like birds and marine mammals take notice.
    The herring spawning in the Central Bay at Alameda Point brought in more harbor seals in December, as reported on my blog, the Alameda Point Environmental Report:

    • Thanks for stopping by and commenting, Richard. I was in a boat outside the Richmond Harbor last weekend and was delighted to see numerous harbor seals there. Am heading to your post now.

    • We were on a boat last weekend and were so fortunate to have a sunny day with quiet waters. I’m happy you enjoyed the photos, Janet, Athena was very busy recording all the beauty around us. The weather this weekend is good too, so we’re going on another boat adventure to Angel Island tomorrow. So great to hear from you, I imagine you are in France right now; I hope your painting and friends adventure have been a joy. My warm thanks.

  6. Great post, Jet. It’s almost identical to what goes on here on Vancouver Island except for the pelicans. We have eagles and seagulls instead, but we do have the sea lions and all the rest of the scenario. Wonderful time of year. I enjoyed your photos.

    • What a delightful addition to the post, Anneli, to hear about the herring run on VI. How exhilarating it must be to see the bald eagles in on this spectacle, too. Many thanks–

      • I hope to do a post on this subject later on when the fishery starts. It won’t be long now. Always so much to see. It was a surprise to me that you have almost the same scene going on where you are. Great to share!

  7. Interesting. All I know is years ago someone told me SF Bay during the herring run was the best time to go catch a sturgeon. They move into the bay to vacuum up the roe. Now I have access to sturgeon in the Snake River, but I haven’t gone after them for a couple of years.

    • Your sturgeon memory backs up the herring post completely, Craig. All the creatures come to the Bay, it’s incredible. How wonderful for you to be near the Snake River. Many thanks–

    • We couldn’t believe it when we saw that sea lion floating out there on his or her back. I’d never seen anything like it before! Several of us on the back of the boat were watching him, wondering if we were seeing it right, and just then the boat guide confirmed that yes, that was a sea lion floating on his back. Thank you, Jan.

  8. What sight to see all the birds and sea animals. Interesting article Jet, about the preservation of the herring and the cooperation with all of the folks involved. Thanks so much for sharing your adventure.

    • It’s a really big deal when the herring come to the Bay. Even people who are not necessarily into nature notice the change in the bird and sea lion activity. I find it interesting, and am really glad you did too, Sharon. Thanks for your interest.

    • Thank you, Dina. It hasn’t always been cooperative, but there’s nothing like the threat of extinction to pull the opposing forces together. And you’re right, it is amazing to watch when it finally happens. So glad you enjoyed the herring post, thank you for your visit and comment. Greetings to beautiful SA.

  9. The Pacific Ocean is so rich in plankton that it’s seemed by many small fish that multiply to massive numbers as you pointed out on your post. Birds, also in numerous quantities seek those fish and the food chain continues. I’ve seen this same cycle in South America and the anchovy vs. a slew of sea birds. Nature at work! Great post my friend as always. Thank you! ๐Ÿ™‚

    • As you say, HJ, nature at work is a marvel to witness, and there’s nothing like watching birds to demonstrate this. Interesting to hear about the anchovies in South America. I looked it up, and it is a similar situation there on the Pacific Coast of Peru, with a history of anchovy population fluctuations due to overfishing. There they have the added problem of El Ninos. We live and learn. Always fun to learn with you, HJ, thank you.

  10. I have seen so many events like this on TV but never in reality . . . apart from a pretty good murmuration display on the west Wales coast. Even on television these gathering events are spectacular so I cannot imagine what seeing the real thing would be like. Lucky you ๐Ÿ˜‰

    • Hi Alastair, it is great fun to share these spectacular events with you here. And you’re right, it is fantastic to witness. The novelist in me looks around to see who else is watching. Are the dog walkers stopping to observe? Are the joggers aware? I overheard two women walking their poodles stop in the middle of their personal conversation to say, “must be the herring” as they stopped to watch for a minute or two. Some people were completely unaware of the event, had their headphone earbuds in, or were in a conversation on their phone. But for the big events, on two different days when the swirl of the activity was flamboyant, every single person stopped in their tracks and watched and marveled. It’s like fireworks. I know you wouldn’t miss it if you were walking along the shoreline, and that’s why it’s so fun to share it with you. Cheers, my friend–

    • It is definitely a cool event, Donna, and the wonderful part is it happens at all times of day in all different coves. It’s starting to wane now this week, I think the spawning is coming to an end. But the migratory ducks will remain here in abundance for another few weeks. I loved that shot of the well-fed sea lion too. Our boat went by him quickly, but Athena was fast. Thanks so much for your visit, Donna, always a pleasure.

    • It is wonderful these days that the importance of the small fish are becoming known and valued for their support in the eco-system. As you say, Sherry, herring, sardines, and others. My pleasure to write the herring post, and share this exchange with you, Sherry.

  11. I can grow nostalgic over herring, since I grew up in a Swedish family in which herring — pickled and otherwise — always was often on our table. The Nordic herring fishery is healthy, and it’s wonderful to read what California is doing to support the herring. Still, struggles with over-fishing continue on the Pacific Coast. This National Geographic article is very interesting. I don’t know how the issues are (or have been) resolved, but your experience and your post give me some hope that resolution will come. Perhaps the cooperation and successes in California can provide guidance to other areas of the world.

    The photos are wonderful. What a great experience it must have been!

    • Thanks for stopping by, Linda. I’m glad you enjoyed the herring article. It is definitely an ongoing work to prevent over-fishing. Some folks depend on the herring for their bread-and-butter, so there’s always a lot to consider in a conservation issue like this. I feel bad in the years they cannot fish, because they suffer a true hardship. I was happy to hear last week from an Audubon conservationist that they meet and talk regularly with the local herring fisherman.

  12. Some days I find myself to be a little lazy, like that relaxing sea lion, just enjoying the scenery and either not seeing or taking things for granted in nature. Thank you for sharing your knowledge and experiences and reminding me how delicate the balance of nature is and all the hard work people and organizations are doing to protect that balance. I enjoyed reading about Richardson Bay and what a wonderful atmosphere it must be for watching the wildlife. Thanks for sharing the great information, links and photos (especially the relaxing sea lion).

    • You always absorb the full theme of my posts, ACI, and I so appreciate your understanding, attentiveness, and support. It is a delicate balance and many people involved with the herring protection, and we are lucky in this country to have so much cooperation and legislation to help keep the balance. I am so happy you enjoyed the relaxing sea lion and the post. I hope you have a jersey for tomorrow’s game.

  13. Thanks, once again, for the lesson about the herring. I can almost imagine what the frenzy of activity must be like. I bet it’s thrilling. Lucky you and lucky us for having you share it. The sea lion raft caused a good chuckle. Thanks to all of Athena’s photography! and you’re such a good teacher.

    • My warm thanks for your kind comment and visit, Gunta. It surely was a frenzy, and yes, it was thrilling…and several times a week for many weeks made for a whale of a time. Sending smiles your way, my friend–

  14. Fascinating! It must be amazing to see when all the conditions are in place for spawning to take place, knowing how that affects such an abundance of species who feed on them. Mahalo!

    • Yes, it was amazing. There was much I did not know, being a temporary resident, but I had a great time observing and educating myself, and enjoying the adventure of sharing it. I am glad you found it fascinating. Sending lots of love and alohas to you, dear Nan.

  15. The interrelationships of nature are intricate and fragile. I’m glad that people with interests in a healthy herring population can work together when needed.

    That must be a fascinating sight. I was just in Sausalito/SF last October/November.

    • So great to have you stop by, Draco. It has been a pleasure to watch the celebration of the herring here in wildlife and humans too. Your visit to the Bay Area during the recent Sonoma County fires might have greeted you with smoky skies? I was evacuated from my home then, and still am. I hope you enjoyed your visit.

      • Thanks, Draco. And I’m sorry you landed in SF on Fleet Week, it could not have been a very peaceful week, but hopefully you enjoyed the Bay Area. I was in SF that Thur. and watched the Blue Angels and they were amazing, perhaps we watched the same sky.

  16. Jet I kept thinking as I read that the noise of all the birds must be deafening. I had no idea about this and as always I am busy learning via your blog.
    How are things for you and Athena? Any dates in sight for return to your home?

    • Hi Sue, welcome back to North America! Yes, the bird noise was loud and so exhilarating, especially the gulls, as you can imagine. I’m glad you enjoyed learning about the herring run. There is no return in sight, as repairs have not yet begun. It has been a frustratingly slow and often harrowing experience. I rely on nature more than ever to lift my spirit. Thank you, Sue, for your inquiries, concern, and the Asian cycling adventures you shared.

      • Always here for you and sending positive energy. We are hoping to return to California in May so will keep in touch about the possibility of spending time together again. Of course only if it works for you. I realize you have a great deal on your plate.

  17. A fascinating and truly informative post, Jet! I am happy to hear that working together the threatening situation has been turned around and well managed. I loved the pictures of relaxing sea lions, in particular.

    • Thank you, Helen, for stopping by and joining the spawning event. I found it fascinating, too, and am delighted to have shared it with you. You and I…we love our local water spots. Take care, my friend–

    • Yes, it sure is a dangerous world for those little herrings. It is amazing any survive at all. And fortunate that the spawning adults do not die, so there is more chance to reproduce. And it is very special that so many people work so hard to encourage and protect this phenomenon. Thank you, Andrea, always a joy to receive your visits and words.

  18. Nature is absolutely fascinating when we observe the chain of life. Fantastic post, Jet, one that I really thank you for sharing. Always when I come here, I learn something from you!! Have a great day!

    • I like the herring visits especially for their reminder of the chain of life and how far it radiates, and I’m really glad you did too, Amy. Always a pleasure to have you stop by, thank you.

    • That relaxing sea lion was so unusual that at first several of us on the boat weren’t quite sure that’s what it was. Great fun to see it, and I’m glad Athena was so quick to capture it so she could share his moments of nirvana. Always a delight, Bertie.

  19. So fascinating! It’s crazy how man will just take and take until we have to save nature. We have a Jellyfish thing going down on the east coast of Canada. We still have lots of Jellyfish, but the Chinese want them, as they have depleted their resources to a pittance. They have offered good money, but there is an uproar from conservation groups. We have some rare endangered giant sea turtles living in those waters, and they eat the Jellyfish. SO, no Jellyfish, no turtles. Nonetheless, it is a bit of a war against the fisheries industry that wants the $$$.

    • The balance is difficult to sustain, especially as human populations balloon. Conservation groups are heroes of the future, and we are lucky to have them. Thank you, Resa, always a pleasure.

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