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  • Growth and natal origin of Pacific hake from the Georgia Basin DPS


Northwest Fisheries Science Center (NWFSC) Fish Ecology FE - Ecosystem Analysis


Pacific hake growth & movement
Growth and natal origin of Pacific hake from the Georgia Basin DPS
Pacific hake (Merluccius productus) is an abundant species residing along the Pacific coast from the Gulf of California to the Strait of Georgia. It is the most common groundfish in the California Current ecosystem (Helser et al. 2008). In Puget Sound, however, Pacific hake populations have declined dramatically in the past three decades (Figure 1), leading to a closure of the fishery in 1990 (Gustafson et al. 2000) and a designation by NOAA Fisheries as a Species of Concern in 1999. Because Pacific hake feed on a variety of fishes and invertebrates, and are an important prey item (for sea lions, small cetaceans, and dogfish sharks), the decline of this mid-trophic level component has important ramifications for the functioning of the Puget Sound ecosystem.
Puget Sound Pacific hake are classified as part of the Georgia Basin Distinct Population Segment (DPS), which is discrete from the highly migratory coastal DPS (Figure 2a). The Biological Review Team (BRT) that reviewed the status of the Georgia Basin DPS noted that in addition to the decline in Puget Sound hake abundance, another cause for concern was a marked decrease in mean hake size and age at maturity (Gustafson et al. 2000). In contrast, these patterns were not observed as strongly in the Strait of Georgia populations (King and McFarlane 2006), which are also part of the Georgia Basin DPS. The BRT were also concerned by uncertainties in the extent of mixing among stocks of the Georgia Basin DPS (Gustafson et al. 2000). This issue is important because if mixing is limited, then the problems faced by the Puget Sound stock are more important for its potential recovery.
Puget Sound hake spawn in large aggregations in a few distinct locations, which are associated with sources of freshwater. Unfortunately these sites occur in somewhat degraded areas, particularly with regard to oxygen concentration. Therefore we hypothesize that the hypoxic and otherwise degraded conditions of these spawning areas have led to depressed juvenile growth, which in turn can have detrimental consequences for the population. Woodbury et al. (1995) found that juvenile growth of the coastal stock varied from year to year and was likely related to environmental conditions. They also speculated that year-class strength might be related to early juvenile growth.
Another goal of the proposed research is to produce an indicator for the Puget Sound marine ecosystem in order to aid in the ongoing development of an Integrated Ecosystem Assessment (IEA) for Puget Sound, which is a high priority for NOAA. Ecosystem indicators should be grounded in the ecology of the system, and juvenile hake growth suits this perfectly because it is not only a reflection of the state of the ecosystem, but is also reflects the viability of an integral component of the ecosystem.
This proposal represents a continuation of a project we initiated last year. In our first year of research, funded by a Species of Concern grant, we obtained the following findings:
1) Otoliths sampled from recent years at the Port Susan spawning site demonstrated much reduced growth rates in the first and second years compared to otoliths sampled there 3 decades ago (Figure 3).
2) The chemical signatures of otolith edges (corresponding to the time when fish were sampled) of fish sampled from the Port Susan spawning site demonstrated strong consistency from year to year. This will enhance our ability to associate adults with their natal origin.
3) The chemical signatures of otolith cores (corresponding to natal areas) demonstrated the potential existence of at least 3 separate sources for adults sampled at the Port Susan site (Fig. 5).
Here we propose to continue this research. In particular, due to staffing issues at DFO, we were not able to obtain archived otolith samples from the Strait of Georgia, which represent an important contrast for the Puget Sound population. We anticipate receiving these otoliths shortly, and analyzing them will prove to be an important component of this research.

Research Themes

Habitats to support sustainable fisheries and recovered populations
Healthy oceans, coastal waters, and riverine habitats provide the foundation for aquatic resources used by a diversity of species and society. Protecting marine, estuarine and freshwater ecosystems that support these species relies on science to link habitat condition/processes and the biological effects of restoration actions. The NWFSC provides the habitat science behind many management actions taken by NOAA Fisheries and other natural resource agencies to protect and recover aquatic ecosystems and living marine resources. The NWFSC also maintains a longstanding focus on toxic chemical contaminants, as a foundation for regional and national research on pollution threats to fisheries and protected resources.
Recovery and rebuilding of marine and coastal species
The Pacific Northwest is home to several iconic endangered species, including Pacific salmon and killer whales, and several rockfish species. Mandates such as the Endangered Species Act, MagnusonStevens Act, and the Marine Mammal Protection Act, grant NOAA Fisheries the authority to manage the recovery of depleted species and stocks. The NWFSC contributes to species recovery through research, monitoring and analysis, providing NOAA managers and regional stakeholders the tools and information they need to craft effective regulations and develop sustainable plans for recovery.

Research Foci

Characterize the interaction of human use and habitat distribution, quantity and quality
The ability to define the state of an ecosystem requires insight into the natural processes within habitats, and how anthropogenic interactions with these processes can alter ecosystems and marine organisms. A wide diversity of human activities -- land use and water withdrawals, industrialization and dredging, fishing practices and climate change (e.g., ocean acidification) -- directly and indirectly impact critical freshwater, estuarine, and marine habitats. To best manage west coast marine, estuarine and freshwater habitats in a sustainable fashion, it is necessary to map the spatial and temporal footprint of human impacts and review their potential biological impact on each species of interest. Measurement parameters will be developed to determine the full range of human impacts using spatial data and improved habitat classification.
Characterize the population biology of species, and develop and improve methods for predicting the status of populations
To evaluate species status and recovery, it is necessary to understand key aspects of the population biology of the species in question. This includes basic information on abundance, age structure, recruitment, spatial distribution, life history and how the species interacts with its ecosystem. For some recovering species, including most overfished groundfish stocks, many ESA-listed Pacific salmon stocks, and high profile species such as Southern Resident killer whales, this basic information is often reasonably well understood. For other recovering species, such as Pacific eulachon and some ESA-listed rockfish species, even basic information (e.g. stock abundance) is unknown. Even for well-studied species, key information on survival rates for critical life stages and how the environment affects these vital rates is lacking. Without basic information on species dynamics, achieving other goals such as quantifying relationships between human activities and species recovery or even knowing if species recovery goals are being met will not be successful. The NWFSC, in partnership with regional stakeholders, including states, tribes and industry, is conducting research to collect and monitor critical demographic information for recovering species.
Develop effective and efficient habitat restoration and conservation techniques
Maintaining and re-establishing viability and sustainability of living marine resources requires conservation and rehabilitation or restoration of habitats upon which species depend. Common habitat restoration approaches and tech-niques often presume that habitats are static features of the environment, and that creation of stable habitats is a desirable restoration strategy. However, riverine, nearshore, and marine habitats are created and sustained by dynamic landscape, climatic, and oceanographic processes and biota are adapted to changing habitats that are within the range of natural variability. Hence, current restoration strategies often have limited success, in part because they fail to recognize larger scale processes that drive habitat change, and in part because they fail to recognize intrinsic habitat potential of individual restoration sites. The main goals of this research focus are to: improve understanding of how large-scale processes create diverse and dynamic habitats that support marine and anadromous species, better understand how human activities alter habitat-forming processes and habitats, develop new restoration techniques that are compatible with sustainable habitat-forming processes, and understand the variety of actions needed to adequately conserve intact critical habitats. In addition, NWFSC’s research will improve understanding of how new and existing habitat restoration and protection techniques affect fish and habitat at multiple scales (i.e., reach, watershed, Evolutionarily Significant Unit).
Develop methods to use physiological, biological and behavioral information to predict population-level processes
Understanding the biological processes occurring within organisms is a powerful way of understanding how environmental changes affect those organisms. Genetics, developmental, physiological and behavioral studies all provide important information for effective species recovery and rebuilding. Integrating this information into models is vital to predict how populations will respond to natural or human perturbations, and to assess the constraints to stock rebuilding efforts. For example, data on thermal tolerance and physiological responses to temperature can be used to explore changes caused by shifts in climate on reproductive behavior and productivity, viability, movement, habitat selection, and population dynamics. Similarly, data on contaminants that impact physiological processes (immune system, growth, development, reproduction, and general health) are critical in determining how these compounds affect population dynamics. Data on biological responses of organisms to ocean acidification are useful for understanding how acidification may affect individual development and survival. The NWFSC collects such information for several species that are of concern, targets of fisheries or otherwise important for overall ecosystem function. NWFSC scientists will continue to expand current efforts and develop methods to incorporate physiological, biological and behavioral data into population models in order to predict population-level processes from these individual level data.


balance organ used to model growth and movement


Growth of pacific hake
Otolith analyses of Pacific hake


Species Merluccius productus
North Pacific hake, Pacific hake, Pacific hake, whiting


Paul Chittaro
Internal Collaborator
Richard Zabel
Principal Investigator