Emerging Concern for Gray Whales in the Eastern North Pacific

For many decades now, it has been generally agreed that the gray whale population that migrates along the west coast of North America, between wintering areas in Mexico and summering areas in Canada, Alaska (USA), and northeastern Russia, represented a conservation “success” story. As described in the most recent (2018) IUCN Red List species assessment, the eastern North Pacific population had recovered strongly from past over-exploitation; the population increased by around 2.5% per year from 1968 through to a peak around 1987/88, after which the population declined, followed by a further recovery to an estimated 26,960 whales (95% confidence interval = 24,420-29,830) based on counts during the 2015/16 southbound migration off California. Unfortunately, things have not gone well since 2016.

Based on the most recent shore-based count during the southward migration between 31 December 2024 and 14 February 2025, scientists from the US National Oceanic and Atmospheric Administration (NOAA) estimated that the migratory population now “most likely” consists of only 11,700 to 14,500 individuals (https://repository.library.noaa.gov/view/noaa/70719). In other words, it has roughly halved since 2016. A June 2025 media release from NOAA revealed that only about 85 mother-calf pairs (95% CI = 55.48-293.5) migrated past the central California observation station between 31 March and 23 May 2025 on their way to feeding grounds in the Arctic. That was the lowest number since records began in 1994.

Calf production in this population has been unusually low since 2018-19 when a so-called “unusual mortality event” began. Between December 2018 and early November 2023, 690 gray whales were found stranded along the coasts of Mexico, the United States, and Canada. The causes of the low calf production and the 2018-2023 die-off are uncertain and this has caused growing concern.

Taken from the 2025 NOAA report on gray whales (Eguchi, Lang, and Weller, “Abundance of eastern North Pacific gray whales 2024/2025,” https://doi.org/10.25923/jqea-s505)

A recent paper on the recovery of baleen whale populations explores the possible links of downturns in abundance to changes in benthic prey availability, while an earlier paper underscored the capacity of gray whales to shift among various benthic and pelagic prey and presented evidence that whales in the eastern Chukchi Sea now routinely feed on krill. Eastern North Pacific gray whales may be an example of a population that is no longer being constrained from full recovery by commercial whaling but is limited in its growth and survival by modern-day threats that are even more challenging to tackle than commercial whaling was.

Gray whale body condition was assessed from aerial (drone) images obtained over multiple years in Laguna San Ignacio, B.C.S., Mexico, revealing large numbers of ‘skinny whales’ during years corresponding with unusual mortality events (UMEs) thought to be related to changes in prey availability. The percentage of “skinny” single whales (gray whales without calves) in “poor” condition peaked at 30% in 2020, declined to 4.6% in 2024 and then increased again to 13% in 2025. Photo credit: “Gray Whale Research in Mexico” team program, http://www.graywhaleresearchmexico.org

The CSG is being asked to reassess the eastern North Pacific gray whale population’s Red List status, and we are hoping to do that once the International Whaling Commission’s Scientific Committee has reviewed the new data and analyses and commented on how the latest findings should be interpreted.

References:

Eguchi, T., Lang, A. and Weller, D. (2005). Abundance of eastern North Pacific gray whales 2024/2025. https://doi.org/10.25923/jqea-s505

Martínez S.A., Swartz, S., Urbán, J.R., Lobo R.B., Díaz, F.C., Romero, A.V., Partida, E.R., Olguín, J.H., Rodríguez, F., and Nuñez, A.J. (2025). Informe de las actividades del monitoreo de la ballena gris (Eschrichtius robustus) temporada invernal 2025 en Laguna San Ignacio, B.C.S. México. https://www.graywhaleresearchmexico.org/updates/2025-annual-gray-whale-report-laguna-san-ignacio-and-bahia-magdalena

International Vaquita Recovery Team Reconvenes

In June 2024 Mexico elected Claudia Sheinbaum as its new President. In the months following her inauguration, Sheinbaum’s administration set out to transform and strengthen fishery management in the Upper Gulf of California, with vaquita conservation as one of its priorities. The International Committee for the Recovery of the Vaquita (CIRVA), which had met officially only once in the preceding 6-year term of President López Obrador, was called back into action. A brief initial “get reacquainted” meeting, chaired by Dr. Marina Robles, Undersecretary for Environmental Policy and Natural Resources at SEMARNAT and Alternate President of the Upper Gulf Sustainability Group, was convened on-line in April 2025.

The newly reconstituted committee then met on-line in a series of virtual sessions on 3-4 and 12 June. All of the CIRVA-12 sessions were chaired by the CSG’s Regional Coordinator for Mexico and Latin America, Lorenzo Rojas-Bracho, who originally recommended the creation of CIRVA to the Government of Mexico, which subsequently announced establishment of the committee in 1997. He has served as its chair ever since.

The first day (3 June) provided CIRVA members with information from the government agencies involved in vaquita conservation but also from NGOs and representatives of the fishing communities.  This direct connection between CIRVA and the fishing communities in the Upper Gulf signals that the new administration is taking a stronger and more proactive approach than the previous administration. While fishermen have participated in and contributed to CIRVA meetings in the past, this renewed engagement is a welcome development.

The CIRVA-12 report includes a summary of discussions, recommendations, a map showing proposed adjustments to the boundaries of designated protected areas, and several annexes. A special section of the CSG website is being created to provide convenient access to all 12 CIRVA reports as well as reports of ad hoc CIRVA meetings and related documents.

Population-specific Data and Policy Support Can Effectively Mitigate Entanglement: a South African example

Bryde’s whale lunge feeding in Plettenberg Bay, South Africa. ©Gwen Penry

By Dr. Gwen Penry*

The inshore population of Bryde’s whales in South Africa was assessed regionally as Vulnerable (using IUCN criteria to apply to the population that is found in the waters off South Africa, Lesotho and Swaziland) owing to its small population size and genetic isolation (Penry et al. 2016). At the time of assessment, a new threat was recognized; fatal entanglement in bottom-mounted fishing gear. Between 2014 and 2020, the South African Whale Disentanglement Network recorded 10 fatal Bryde’s whale entanglements, 6 of which were in gear used for an exploratory octopus fishery. Examination of the carcasses revealed that most had rope through the mouth, indicating that the whales had been feeding at the time of entanglement. Identifying the behaviour leading to such incidents became a research priority. In April 2018 and 2019 scientists deployed suction-cup data loggers on 12 Bryde’s whales in Plettenberg Bay in the hope that they would provide data to explain the entanglement process.

They did! Data from the loggers revealed a novel behaviour: Bryde’s whales chase prey near the seafloor at high speeds (up to 7.4 m/s), followed by upward lunges and mouth opening (Segre et al., 2022). This explained how the rope connecting the octopus traps became lodged in the whale’s mouths, anchoring them to the seafloor.

The original gear configuration for the octopus fishery included a set of traps (~30) spaced 10–20 m apart connected by floating groundlines that arc up into the water column. This design was intended to minimize damage to reefs, facilitate gear retrieval, and allow sufficient slack in the rope for an entangled whale to surface and breathe until disentanglement teams arrived. The same configuration had been used elsewhere (e.g. Australia) without major incident and was therefore not expected to be a fatal entanglement concern in South Africa.

In 2019, while the tagging fieldwork was still underway, two Bryde’s whales died from entanglement in this gear and the Minister of Forestry, Fisheries and the Environment implemented a temporary moratorium on the fishery and called an urgent meeting with her advisors, fishery representatives and scientists. Several options to mitigate whale-gear interactions were discussed, including seasonal closures. However, because Bryde’s are resident in South African coastal waters, seasonal closures would not help, as they would for migratory species such as humpback and southern right whales. The only viable option whereby the fishery could continue without entanglements was to remove all rope from the water column by using sinking groundlines and acoustic or time-release surface-marker buoy lines. Revised regulations were issued specifying required gear modifications. Replacement of floating line with sinking line is extremely expensive and, because the fishery was still in an exploratory phase, only one of the permit holders was prepared and able to invest in the necessary gear modifications. Since then (late 2019), no entanglements have been reported. The mitigation measures, though provisionally deemed successful, remain to be fully tested if the fishery becomes active at a larger and commercial scale.

Lessons learned

This situation highlights the importance of conducting science-based risk assessments before, and indeed while, new fisheries are explored. Although the original octopus gear configuration apparently had not led to fatal whale entanglements elsewhere, the unique behavior of Bryde’s whales in South Africa led to unfortunate deaths in this Vulnerable population.

Fortunately, there were only a few active permit holders (6) at the time, which allowed for manageable discussions and interactions with scientists and decision-makers. New fisheries being explored should begin with a limited number of allocated permits, to allow any issues to be resolved amongst a small group of people, and before large investments are made.

This example shows that location- and species-relevant science can support solutions to at least some bycatch problems. The South African government acted decisively to make data-driven policy changes and are commended for their swift action. It remains to be seen whether the mitigation measures will be effective and allow for large-scale expansion of the octopus fishery. The novel finding that Bryde’s whales use high-speed chases near the seafloor to catch their prey highlights the value of using species-specific, behaviour-based information to support conservation and management recommendations.

Bryde’s whale in Plettenberg Bay, South Africa. ©Gwen Penry

Research team investigating a Bryde’s whale that died from entanglement in lines of experimental octopus fisheries in South Africa. ©Gwen Penry

1. Penry G, Findlay K, Best P. 2016. A conservation assessment of Balaenoptera edeni. In Child MF, Roxburgh L, Do Linh San E, Raimondo D, Davies-Mostert HT, editors. The Red List of Mammals of South Africa, Swaziland and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.
2. Segre, PS; Di Clemente, J; Kahane-Rapport, SR; Gough, WT; Lombard, A.T; Goldbogen JA; Penry, GS(2022). High-speed chases along the seafloor put Bryde’s whales at risk of entanglement. Conservation Science and Practise, 4(5). https://doi.org/10.1111/csp2.12646

*Dr Gwen Penry
Research Associate – Nelson Mandela University, Institute for Coastal and Marine Research
Research Fellow – University of Pretoria, Mammal Research Institute Whale Unit
IUCN SSC CSG member

https://orcid.org/0000-0003-0545-7723