Short answer: Herring oil is fish oil extracted from Atlantic herring (Clupea harengus) and Pacific herring (Clupea pallasii) — small, lipid-rich pelagic schooling fish at a relatively short food-chain position. Per Bourre 2003 (Reprod Nutr Dev) and standard fish-oil references, herring oil typically contains 12–18 percent EPA (eicosapentaenoic acid) plus DHA (docosahexaenoic acid) by total fatty acids — comparable to salmon oil density. Per Bauer 2007/2008/2011 (JAVMA) canine omega-3 review framework, what matters clinically is total EPA + DHA delivery rather than the specific fish source. Major Atlantic herring stocks are ICES-managed and MSC-sustainable; some Pacific herring stocks vary by region. Shorter food-chain position than salmon means lower mercury and PCB accumulation per FAO 2023 (State of World Fisheries). AAFCO 2024 Official Publication accepts herring oil and herring meal as pet-food ingredients. The KibbleIQ rubric treats herring oil as equivalent to salmon oil, sardine oil, and anchovy oil for marine omega-3 credit.

The species — Atlantic and Pacific herring

Per FAO 2023 (State of World Fisheries) species characterization and standard ichthyology references, the genus Clupea contains two closely related species important to commercial fisheries and pet-food ingredient supply. Atlantic herring (Clupea harengus) is distributed throughout the Northeast and Northwest Atlantic and is one of the most abundant pelagic fish species globally. Pacific herring (Clupea pallasii) is distributed through the Eastern and Western North Pacific. Both are small, schooling, pelagic, planktivorous forage fish, typically 25–40 cm in adult length, feeding primarily on zooplankton and small fish larvae. Their short food chain (small fish that eat plankton) means they accumulate substantially less of the heavy metals and persistent organic pollutants that biomagnify up the food chain in predatory species.

Both species are lipid-rich, with adult body fat typically 15–20 percent during pre-spawning condition (when most commercial catch occurs). The high body-fat content makes them an efficient industrial source of marine oil. The remaining body solids are processed into herring meal — a high-protein, high-mineral fish meal used in both human food (in some markets), aquaculture feed, and pet food. Pet-food labels may list either "herring oil" (the lipid extract) or "herring meal" (the protein-mineral concentrate, which contains residual oil providing some EPA + DHA contribution alongside its protein contribution).

The biochemistry — EPA + DHA density and fatty acid profile

Per Bourre 2003 (Reprod Nutr Dev) fish oil composition review and standard analytical references, herring oil’s typical EPA + DHA composition is 12–18 percent of total fatty acids, with EPA usually slightly higher than DHA in the Atlantic species and roughly equal in the Pacific species. The remaining fatty acid composition includes substantial saturated fatty acids (palmitic acid, myristic acid), monounsaturated fatty acids (oleic acid, gadoleic acid 20:1n-9, and the species-distinctive cetoleic acid 22:1n-11), and minor amounts of other long-chain omega-3 species including DPA (docosapentaenoic acid 22:5n-3) and ALA (alpha-linolenic acid 18:3n-3).

Per Bauer 2007/2008/2011 (JAVMA) canine omega-3 review framework, the clinical EPA + DHA delivery from a fish oil depends on the inclusion rate of the oil and the species-specific EPA + DHA density. Herring oil at 5 percent dietary inclusion delivers approximately 0.6–0.9 percent EPA + DHA in the final formulation, which is in the range supported by canine clinical trials for anti-inflammatory effects (joint, skin, cardiovascular) at typical adult-dog body weights. The companion oxidation-stability question (omega-3 fatty acids are prone to lipid peroxidation in storage) is addressed by mixed-tocopherol antioxidant addition during oil processing and by opaque packaging in the finished product.

Sustainability and supply — ICES-managed stocks and MSC certification

Per ICES 2024 (International Council for the Exploration of the Sea) annual stock assessments and FAO 2023 (State of World Fisheries) sustainability reviews, the major Northeast Atlantic herring stocks — Norwegian spring-spawning herring, North Sea autumn-spawning herring, Baltic herring, Celtic Sea herring — are managed under quota systems agreed by coastal state cooperation (EU, Norway, Faroe Islands, Iceland). Most are at biomass levels above precautionary reference points and several are MSC (Marine Stewardship Council) certified. Atlantic herring is therefore considered one of the more sustainable wild-capture marine ingredient sources for pet food.

Per CCAMLR 2019 (Antarctic context) and the Pacific Fishery Management Council Pacific herring assessments, Pacific herring (Clupea pallasii) has a mixed sustainability picture. Some Eastern Pacific stocks (Sitka Sound, British Columbia central coast) are healthy; others (California coast, lower Columbia River) have collapsed-and-rebuilding histories. Pet-food manufacturers sourcing herring oil from MSC-certified or ICES-managed Atlantic stocks have a defensible sustainability story. Those sourcing from unspecified regions should be evaluated case-by-case. The KibbleIQ rubric does not currently differentiate scoring based on fishery certification because supply-chain documentation is rarely transparent to consumers; it is a trust-signal consideration rather than a rubric-defined penalty.

Comparison with peer marine oils

Per Bauer 2007/2008/2011 (JAVMA) and Calder 2017 (Biochem Soc Trans), the marine fish oil category includes several functionally similar sources with overlapping EPA + DHA delivery: salmon oil (12–18 percent EPA + DHA), sardine oil (~25 percent EPA + DHA in concentrated forms, higher than herring), anchovy oil (~20 percent EPA + DHA), herring oil (12–18 percent EPA + DHA), menhaden oil (15–25 percent EPA + DHA), and krill oil (12–17 percent EPA + DHA in phospholipid-bound form which has somewhat different absorption kinetics per Schuchardt 2011). All deliver the same clinical mechanism of EPA + DHA support; the practical differences are in sustainability profile, contaminant load, and price.

Herring oil has a sustainability advantage versus salmon oil for the Atlantic stocks, a comparable EPA + DHA density, a lower mercury and PCB load than salmon owing to the shorter food-chain position, and a typically lower ingredient cost per gram of EPA + DHA delivered. Cod liver oil is functionally similar on EPA + DHA but includes substantial concentrated vitamin A and D that require separate consideration in AAFCO-complete formulation per Hall 1996 (Vet Med) vitamin A toxicity work. The KibbleIQ rubric treats herring oil, salmon oil, sardine oil, and anchovy oil as functionally equivalent for marine omega-3 credit.

How KibbleIQ scores herring oil

The KibbleIQ Dry Kibble Rubric awards marine omega-3 credit for herring oil at the same tier as salmon oil, sardine oil, anchovy oil, and krill oil. The credit applies when the fish-oil ingredient appears with sufficient inclusion to deliver meaningful EPA + DHA (typically 1–5 percent of the formulation, contributing 0.1–1 percent EPA + DHA to the final diet). The rubric does not double-count credit across multiple marine oil ingredients in the same formulation. The rubric’s strongest anti-inflammatory tier combines marine EPA + DHA plus mixed tocopherols (oxidation protection) plus other functional adjuncts per the AAHA 2022 Pain Management framework.

To check whether your dog’s food carries marine omega-3 ingredients, paste the ingredient list into the KibbleIQ analyzer. For peer marine oil context, see our omega-3 fatty acids explainer, salmon oil explainer, sardine oil explainer, anchovy oil explainer, krill oil explainer, algae oil explainer, and cod liver oil explainer. For broader context, see best dog food for joint problems and our KibbleIQ methodology page.