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Open Access Publications from the University of California

Outreach and educational component of California Sea Grant Extension Advisors, a network of eight marine specialists.

Cover page of Effects of Flow-Related Variables on Oversummer Survival of Juvenile Coho Salmon in Intermittent Streams

Effects of Flow-Related Variables on Oversummer Survival of Juvenile Coho Salmon in Intermittent Streams


While many studies have established the importance of streamflow as a driver of fish population dynamics, few have examined relationships between survival of juvenile salmonids and flow-related variables in intermittent streams. With predictions for higher frequency of drought conditions due to climate change, and the associated increasing human demand for water during the dry season, understanding fish­­­–flow relationships is becoming increasingly important for the protection of sensitive aquatic species. To examine the effects of low streamflow on juvenile salmonids rearing in small intermittent streams, we estimated survival and collected environmental data in four coastal California watersheds from 2011 to 2013. We used an individual-based mark-recapture modeling approach to evaluate the influence of flow-related variables on oversummer survival of PIT-tagged juvenile Coho Salmon stocked into eight stream reaches. Survival was positively associated with streamflow magnitude, wetted volume, and dissolved oxygen, and negatively associated with days of disconnected surface flow (days of disconnection), and temperature. Days of disconnection best explained survival, though the relationship varied by geomorphic reach type. Survival was lower in alluvial reaches as compared to bedrock and clay reaches, and showed a faster rate of decline with increasing days of disconnection and drought condition. In all reaches, the onset of pool disconnection represented a turning point at which water quality, water quantity, and survival declined. For this reason, we suggest that days of disconnection (or the flow magnitude at which pools become disconnected) is a useful metric for identifying flow-impaired reaches, informing streamflow protection strategies, and prioritizing streamflow enhancement efforts designed to benefit sensitive salmonid populations in intermittent streams.

Calcifying algae maintain settlement cues to larval abalone following algal exposure to extreme ocean acidification


Ocean acidification (OA) increasingly threatens marine systems, and is especially harmful to calcifying organisms. One important question is whether OA will alter species interactions. Crustose coralline algae (CCA) provide space and chemical cues for larval settlement. CCA have shown strongly negative responses to OA in previous studies, including disruption of settlement cues to corals. In California, CCA provide cues for seven species of harvested, threatened, and endangered abalone. We exposed four common CCA genera and a crustose calcifying red algae, Peyssonnelia (collectively CCRA) from California to three pCO2 levels ranging from 419–2,013 µatm for four months. We then evaluated abalone (Haliotis rufescens) settlement under ambient conditions among the CCRA and non-algal controls that had been previously exposed to the pCO2 treatments. Abalone settlement and metamorphosis increased from 11% in the absence of CCRA to 45–69% when CCRA were present, with minor variation among CCRA genera. Though all CCRA genera reduced growth during exposure to increased pCO2, abalone settlement was unaffected by prior CCRA exposure to increased pCO2. Thus, we find no impacts of OA exposure history on CCRA provision of settlement cues. Additionally, there appears to be functional redundancy in genera of CCRA providing cues to abalone, which may further buffer OA effects.

Cover page of Readying California Fisheries for Climate Change

Readying California Fisheries for Climate Change


This document provides scientific guidance to the California Department of Fish and Wildlife (CDFW) regarding the potential impacts of climate change on California fisheries and recommendations for building resilience to buffer climatic forces. At CDFW’s request, the California Ocean Protection Council (OPC) provided funding to the Ocean Science Trust (OST) to convene an OPC Science Advisory Team (OPC-SAT) Working Group with relevant ecological, social science, and governance expertise. This guidance was prepared by OST and the OPC-SAT Working Group in partnership with CDFW, in adherence with the requirements in the OPC Staff Recommendation: “California State Fisheries Management: Current Efforts and Future Needs.” This project was developed for consideration by the California Department of Fish and Wildlife (CDFW) to help inform the state’s process to amend the Marine Life Management Act (MLMA) Master Plan. Products from this project have been submitted to CDFW for review and may be integrated, in full or in part, into a draft Master Plan Amendment. In addition, given the broad potential ecological, social and economic impacts from climate change, we hope the document provides useful guidance for other government agencies and departments, funders, affected individuals and communities, and non-governmental organizations engaging in action on this issue. Additional information about the Master Plan amendment process, including key resources and opportunities for stakeholder engagement, is available at

The Resilience of Marine Ecosystems to Climatic Disturbances


The intensity and frequency of climate-driven disturbances are increasing in coastal marine ecosystems. Understanding the factors that enhance or inhibit ecosystem resilience to climatic disturbance is essential. We surveyed 97 experts in six major coastal biogenic ecosystem types to identify “bright spots” of resilience in the face of climate change. We also evaluated literature that was recommended by the experts that addresses the responses of habitat-forming species to climatic disturbance. Resilience was commonly reported in the expert surveys (80% of experts). Resilience was observed in all ecosystem types and at multiple locations worldwide. The experts and literature cited remaining biogenic habitat, recruitment/connectivity, physical setting, and management of local-scale stressors as most important for resilience. These findings suggest that coastal ecosystems may still hold great potential to persist in the face of climate change and that local- to regional-scale management can help buffer global climatic impacts.

Cover page of Can the United States have its fish and eat it too?

Can the United States have its fish and eat it too?


As domestic affluence increases, nations advocate for conservation policies to protect domestic biodiversity that often curtail natural resource production activities such as fishing. If concomitant consumption patterns remain unchanged, environmentally-conscious nations with high consumption rates such as the U.S. may only be distancing themselves from the negative environmental impacts associated with consuming resources and commodities produced elsewhere. This unintended displacement of ecosystem impacts, or leakage, associated with conservation policies has not been studied extensively in marine fisheries. This paper examines this topic, drawing on case studies to illustrate the ways in which unilateral marine conservation actions can shift ecosystem impacts elsewhere, as has been documented in land use interventions. The authors argue that the U.S. should recognize these distant ecological consequences and move toward greater self-sufficiency to protect its seafood security and minimize leakage as well as undertake efforts to reduce ecosystem impacts of foreign fisheries on which it relies. Six solutions are suggested for broadening the marine conservation and seafood consumption discussion to address U.S.-induced leakage.

Cover page of Local Seafood Availability in San Diego, California Seafood Markets

Local Seafood Availability in San Diego, California Seafood Markets


Like many developed coastal cities, San Diego, California has strong geographic and recreational ties to the adjacent ocean, but weak culinary ones. Less than 10% of the seafood consumed in the U.S., and San Diego in particular, is domestic. The popularity and abundance of farmers’ markets and other local markets in San Diego indicates an interest among producers and the public alike in cultivating local, diverse food systems, but this trend has been slower to catch on for seafood. The goal of this project was, therefore, to define and begin to understand the influences on the patterns of locally sourced, domestic seafood availability in San Diego. This study focused on seafood availability in seafood markets including researching market websites and contacting seafood counter managers to determine the general frequency (consistent, occasional, none) at which the markets sold seafood produced by San Diego fishermen or aquafarmers. Seafood market locations were mapped, and demographic and spatial information was gathered for each market’s zip code. The results of the study revealed that only 8% of San Diego’s 86 seafood markets consistently carried San Diego-sourced seafood, and 14% of markets carried it on occasion. Increased density of these local seafood markets was correlated with proximity to the coast, with almost 80% of the markets located within 2 km of the coast. Neither per capita income nor racial diversity was correlated with local seafood market density, indicating that factors contributing to coastal isolation matter more than wealth or diversity in determining where local seafood is sold. The geographic disparity in local seafood availability may be due to a variety of factors, including a small fishing fleet, prevalence of imported seafood, limited waterfront and urban infrastructure needed to support a local seafood system, and a lack of public awareness about local fisheries. Information gleaned from this study can inform further investigation into the influences on local, equitable seafood systems, as well as help consumers, producers and marketers to make informed decisions about seafood purchases and marketing efforts.

Cover page of Collaborative fisheries research to build socioeconomic essential fishery information: A test case

Collaborative fisheries research to build socioeconomic essential fishery information: A test case


Fisheries are integrated social-­‐ecological systems, characterized by dynamic and complex interactions within and between the natural and human environments. California’s 1998 Marine Management Life Act (MLMA) recognizes the role of people in fisheries, and the MLMA Master Plan calls for the inclusion of socioeconomic as well as ecological “essential fishery information” in fishery management plans. However, critical gaps in such information for virtually all fisheries hinder managers’ ability to actively adapt and communities’ ability to plan for the future. This project begins to meet such information needs for the commercial fishery for California halibut, providing an example for other fisheries. We conducted a small collaborative fisheries research (CFR) project that engaged fishery participants, scientists and managers. Our goal was to produce sound social scientific understanding of the human dimensions of the fisheries system that is useful to the fishing, management, and scientific communities. We used an iterative approach, integrating analyses of data from the state’s California Fisheries Information System (CFIS), the literature, and knowledgeable fishery participants, managers and scientists to build understanding about the fishery’s human system and its dynamics. The research focused on the period 2000-­‐2012 to capture recent changes in the fishery and the larger fishery system, with events prior to and since also informing our efforts.

Cover page of Integrating collaborative data collection with management: A lobster fishery test case

Integrating collaborative data collection with management: A lobster fishery test case


Cost-effective programs for gathering essential fisheries information (EFI) are critically needed to

improve the data-poor state of fisheries in California and worldwide. The California Marine Life

Management Act (MLMA) recognizes this need and requires development of fishery management

plans (FMPs) that identify suitable protocols for collecting data, and use of the best available

scientific information to inform management. Furthermore, in the United States, several state

and federal laws require the engagement of fishermen and others in fisheries management. To

address these needs, we developed a collaborative at-sea sampling program (CASP) by:

• determining the key regulatory, administrative and operational features of established

collaborative fisheries data collection programs,

• developing a robust sampling design with associated protocols for the commercial

California spiny lobster fishery,

• designing, testing and modifying data collection and management components of the

sampling program, and

• exploring options for sustaining the program into the future.

The goal of the program was to provide a model for generating an ongoing stream of diverse data

and interpretation for integration into management, thereby supporting use of more

sophisticated and robust models for managing California fisheries.

We used the California commercial fishery for spiny lobster, for which an FMP is being developed,

as a test case. This project built upon earlier work by the co-PIs developing a CASP for California’s

southern rock crab commercial fishery (Culver et al. 2010) and by Neilson to implement a lobster

fishery data collection program similar to one used in the New Zealand rock lobster fishery.