{"id":5060,"date":"2026-10-21T21:39:19","date_gmt":"2026-10-22T04:39:19","guid":{"rendered":"https:\/\/calsport.org\/fisheriesblog\/?p=5060"},"modified":"2026-10-21T21:39:19","modified_gmt":"2026-10-22T04:39:19","slug":"el-nino-effects-on-california-salmon","status":"publish","type":"post","link":"https:\/\/calsport.org\/fisheriesblog\/?p=5060","title":{"rendered":"El Ni\u00f1o Effects on California Salmon"},"content":{"rendered":"

In a September 28, 2025 post<\/a>, I was optimistic about the 2026 salmon season following wetter years 2023-2025.\u00a0 I expected strong recruitment from the tens of millions of hatchery smolts released in 2023 and 2024, in combination with the almost complete closure of salmon fishing in 2023-2025. \u00a0What I failed to sufficiently account for was the 2023- El Ni\u00f1o and the companion Blob, though I did recognize some concerns.1<\/a><\/sup> Now we are facing a projected \u201cSuper El Ni\u00f1o\u201d in 2026 and 2027. \u00a0I should have anticipated potential adverse effects on the salmon ready to make their runs in 2026.<\/p>\n

NOAA had been issuing warnings about a strong El Ni\u00f1o and the potential for adverse ocean effects, for example in June 2026<\/a> (see excerpt below).<\/p>\n\n\n\n
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Tough Times for Salmon<\/em><\/h2>\n

Warming can be harmful to salmon, whether in the freshwater or saltwater chapters of their life cycle. Low snowpack that preceded the Blob combined with atmospheric patterns that blocked cooling winds. A severe California drought also left little cold water in Shasta and other reservoirs. As western rivers warmed to lethal temperatures for salmon, managers had no way to offset the heat. About 95 percent of the eggs spawned by endangered winter-run Chinook salmon in the Sacramento River died in 2015. Current conditions are similar, with record-low snowpack across most of the Western United States, although reservoir storage is much better than it was in 2015.<\/em><\/p>\n

Young salmon also faced difficulties in the ocean during the Blob and El Ni\u00f1o years, since warmer ocean waters typically lack the high-energy prey juvenile salmon depend on for rapid growth during their first months after entering saltwater. That lack of quality prey reduces their odds of survival, which in turn reduces the chances they will return to rivers and support coastal fisheries as adults 1 to 3 years later. The years following the Blob brought weak salmon returns to many rivers along the West Coast, leading to 2017 closures of salmon fishing along parts of the California and Oregon Coasts. Some salmon stocks, such as Oregon Coast coho, fared better, though, as different stocks rely on different parts of the ocean affected differently by the warming influences.<\/em><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Six strong El Ni\u00f1os have occurred in the last five decades (Figure 1), including the ongoing El Ni\u00f1o in 2026.\u00a0 Salmon escapement to spawning rivers in the Central Valley was depressed during or following El Ni\u00f1o years (Figures 2 and 3).\u00a0 It now appears that the 2026 forecasted escapement may be depressed because of the Super El Ni\u00f1o.\u00a0 \u00a0Salmon returns to date are less than expected.<\/p>\n

Warm water and lack of upwelling, along with the influx of warm southern waters along the California coast, characterize El Ni\u00f1o conditions.\u00a0 Southern predatory fish such as tuna species (bonito, albacore, and bluefin) move north with the warmer waters, which creates another concern.\u00a0 Changes in the salmon prey, such as more anchovy and less herring and krill, reduce overall forage and have led to thiamine deficiency in the adult salmon spawning stocks.<\/p>\n

Escapement numbers plummeted during past El Ni\u00f1o periods.\u00a0 Droughts were also often associated with El Ni\u00f1os.\u00a0 Droughts reduce the number of salmon smolts that reach the ocean.\u00a0 El Ni\u00f1o conditions generally lead to lower survival of juvenile and adult salmon in the ocean.<\/p>\n

We will have to wait to see the effect of the ongoing El Ni\u00f1o phenomenon on salmon escapement to Central Valley rivers.\u00a0 Lingering effects of low escapement in 2023 and 2024 from the 2020-2022 drought and from the 2023 El Ni\u00f1o may result in low in-river (non-hatchery) spawning escapement.\u00a0 Both in-river and hatchery escapement in 2026 may well be depressed. Escapement in 2027 and 2028 may also be affected from lower survival from broodyears 2025 and 2026 in the ocean during the 2026 Super El Ni\u00f1o.<\/p>\n

It is important to remember that the effects of El Ni\u00f1o conditions on salmon do not take place in isolation.\u00a0 Depressed escapement of salmon adults and depressed survival of juvenile salmon to the ocean today occurs in the context of long-term declines.\u00a0 Much as a major health crisis has a particularly severe effect on an already unhealthy patient, the effects of El Ni\u00f1o conditions on salmon in 2026 are likely to have outsized effects on California salmon populations that have struggled over the last two decades, even in relatively good years.<\/p>\n

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Figure 1. El Ni\u00f1o Index 1990-2025 along Central California coast. Source: NOAA.<\/p><\/div>\n

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Figure 2. Escapement estimates of winter-run salmon from spawning ground (in-river) surveys 1970-2025. Red outlines indicate El Ni\u00f1o years (from Figure 1). Source: CDFW.<\/p><\/div>\n

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Figure 3. Escapement estimates of fall-run salmon from spawning ground (in-river) surveys 1952-2025. Red outlines indicate El Ni\u00f1o years (from Figure 1). Source: CDFW.<\/p><\/div>\n

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  1. https:\/\/calsport.org\/fisheriesblog\/?p=4599<\/a> ↩<\/a><\/span><\/li>\n<\/ol>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

    In a September 28, 2025 post, I was optimistic about the 2026 salmon season following wetter years 2023-2025.\u00a0 I expected strong recruitment from the tens of millions of hatchery smolts released in 2023 and 2024, in combination with the almost … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_post_was_ever_published":false},"categories":[13,12],"tags":[],"class_list":["post-5060","post","type-post","status-publish","format-standard","hentry","category-chinook","category-water-quality"],"jetpack-related-posts":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/posts\/5060","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5060"}],"version-history":[{"count":5,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/posts\/5060\/revisions"}],"predecessor-version":[{"id":5068,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=\/wp\/v2\/posts\/5060\/revisions\/5068"}],"wp:attachment":[{"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5060"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5060"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/calsport.org\/fisheriesblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5060"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}