Salvador E. Lluch-Cota

Coastal upwelling in the eastern Gulf of California

Abstract Understanding and quantifying upwelling is of great importance for marine resource management. Direct measurement of this process is extremely difficult and observed time-series do not exist. However, proxies are commonly derived from different data; most commonly wind-derived. A local wind-derived coastal upwelling index (CUI) is reported for the period 1970–1996 and is considered representative for the eastern central Gulf of California, an important fishing area where no proxies exist. The index is well related to pigment concentration distribution, surface water temperature, and population dynamics of important fish resources over the seasonal time-scale. There is a biological response to ENSO activity not reflected by this index, indicating that improvement of biological enrichment forecasting also requires water column structure input. A clearly increasing seasonal amplitude signal is detected in the coastal upwelling index and sea surface temperature since the mid 1970s. Understanding the nature of these long-term trends, the incorporation of remote tropical ocean signals into the enrichment proxy, the dynamics of atmosphere and ocean, and the biological responses are major challenges to the proper management of fish resources in the Gulf of California. upwelling / Gulf of California / seasonality / climate change

Distribution and abundance of the Pacific sardine (Sardinops sagax) in the Gulf of California and their relation with the environment

Abstract In 1989–90 the small pelagic fishery of the Gulf of California began to show a very marked decline in the catch of its main component, the Pacific sardine (Sardinops sagax). The catch plummeted from 292,000 t in 1988–89 to 7000 t in 1991–92 and 1992–93. This caused a serious economic crisis in the local fishery fleet and industry, and resulted in the loss of 3000 jobs. In 1993–94 the fishery showed signs of recovery as the abundance of the Pacific sardine began to recover. The catch improved to 128,000 t in 1993–94 and further to 215,000 t in 1996–97. In trying to understand this great variability, we proposed the hypothesis that the distribution and the abundance of the Pacific sardine of the Gulf of California is determined by the wind patterns (upwelling) and the sea surface temperature. The results of analyzing data from 25 cruises showed the period of low relative abundance between 1990 and 1993 and one of high abundance between 1993 and 1996. The range of the sardines distribution expanded as its abundance increased and contracted when abundances were low. The relationship between the abundances of the sardine and environmental variables proved to nonlinear and bell-shaped. The adjusted pattern explained 78.8% of the variability of the sardine abundance. The highest abundance are produced by moderate upwelling (13–18 m3s−1 per 10 m of coastline) and sea surface temperatures of between 19°C and 25°C.

Issues of ecosystem-based management of forage fisheries in “open” non-stationary ecosystems: the example of the sardine fishery in the Gulf of California

The Gulf of California system presents major challenges to the still developing frameworks for ecosystem-based management (EBM). It is very much an open system and is intermittently subject to important influxes of migratory visitors, including large pelagic predatory fishes and small pelagic forage fishes. These migrants include the more tropical species from the coastal ecosystems to the south and perhaps subtropical sardines and anchovies from the California Current upwelling system. In addition to the multi-annual ENSO-scale and what may seem to be rather erratic episodes of major population incursions, the Gulf presents nonstationary, transient aspects on a variety of longer time scales. Moreover, the removal of top predators by commercial and sport fisheries has introduced trends that must be affecting the entire ecosystem, and certainly the forage fishes that are their major prey base. In addition to size limits, fishing seasons, area closures and license limitations, the fishery is managed by an ad hoc adaptive management system, in which the fishing season can be shortened or additional areas closed to fishing if pre-season exploratory fishing surveys indicate a shortage of small pelagic fishes on the fishing grounds. Whether this system is likely to be sustainable in the long term is difficult to determine, given the potential for rapid changes in the system because of environmental changes and/or feedbacks within the food web. Thus it appears that innovative management frameworks, among other things utilizing the comparative method, may be required in order to determine defensible tradeoffs between precaution and resource utilization.

Baja California's biological transition zones: Refuges for the California sardine

The information on the transitional areas between the temperate and tropical domains at the southern extent of the California Current System is reviewed and described, particularly searching for the relative isolation or interchange between the western coast of the Baja California peninsula and the Gulf of California, as well as mechanisms that permit the existence of sizeable stocks of California sardine. Biological Action Centers that have high productivity throughout the year, as opposed to the rest of the coastal area, are found in both the western coast of the peninsula at the Sebastián Vizcaíno—Punta Eugenia region and in the Ballenas Channel inside the gulf; these features support large biomasses of sardine throughout the full year and serve as long term refuges during adverse periods. The role of the Sebastián Vizcaino sardine stock as the primary group for expansion is examined.

A system-wide approach to supporting improvements in seafood production practices and outcomes

Environmental certification and consumer awareness programs are designed to create market incentives for implementing fisheries and aquaculture practices that are more sustainable. Typically focused on particular species and activities, such programs have so far triggered few changes to improve seafood sustainability. Here, we present a conceptual, system-wide fisheries and aquaculture certification program designed to recognize and promote change toward more sustainable and resilient seafood production systems. In contrast to previous efforts, this program concentrates on both ecosystems and various human stakeholders, relies on an adaptive management approach (termed “continual improvement”) to enhance outcomes, and considers socioeconomic factors. The goal of this program is to support the restoration and maintenance of healthy ecosystem states and thriving human communities as well as the improvement of whole social–ecological systems.

A regional-scale sustainable development index: the case of Baja California Sur, Mexico

SUMMARY Sustainable development, as a multi-dimensional concept, is difficult to measure. Some efforts using indicators and indices have appeared in recent years, but most were developed on a national scale. Use of sustainability indicators has proven valuable for attaining better management of the environment by minimizing information gaps and maximizing community capabilities in terms of economic, social, environmental, and institutional sustainability dimensions. However, at least in the case of developing countries, the potential exists that national sustainability measures, based on national level indicators, may mask problems in sub-national zones with highly unsustainable conditions. This paper proposes a methodology to evaluate sustainable development at a local level, the use of which could be helpful in comparing different regions within a country or even among different countries. National sustainability indicators should result from a combination (whether additive or proportional) of regional sustainability indicators, as developed in this paper.

Key impacts of climate engineering on biodiversity and ecosystems, with priorities for future research

Abstract Climate change has significant implications for biodiversity and ecosystems. With slow progress towards reducing greenhouse gas emissions, climate engineering (or ‘geoengineering’) is receiving increasing attention for its potential to limit anthropogenic climate change and its damaging effects. Proposed techniques, such as ocean fertilization for carbon dioxide removal or stratospheric sulfate injections to reduce incoming solar radiation, would significantly alter atmospheric, terrestrial and marine environments, yet potential side-effects of their implementation for ecosystems and biodiversity have received little attention. A literature review was carried out to identify details of the potential ecological effects of climate engineering techniques. A group of biodiversity and environmental change researchers then employed a modified Delphi expert consultation technique to evaluate this evidence and prioritize the effects based on the relative importance of, and scientific understanding about, their biodiversity and ecosystem consequences. The key issues and knowledge gaps are used to shape a discussion of the biodiversity and ecosystem implications of climate engineering, including novel climatic conditions, alterations to marine systems and substantial terrestrial habitat change. This review highlights several current research priorities in which the climate engineering context is crucial to consider, as well as identifying some novel topics for ecological investigation.

Recent trends in sea surface temperature off Mexico

Changes in global mean sea surface temperature may have potential negative implications for natural and socioeconomic systems; however, measurements to predict trends in different regions have been limited and sometimes contradictory. In this study, an assessment of sea surface temperature change signals in the seas off Mexico is presented and compared to other regions and the world ocean, and to selected basin scale climatic indices of the North Pacific, the Atlantic and the tropical Pacific variability. We identified eight regions with different exposure to climate variability: In the Pacific, the west coast of the Baja California peninsula with mostly no trend, the Gulf of California with a modest cooling trend during the last 20 to 25 years, the oceanic area with the most intense recent cooling trend, the southern part showing an intense warming trend, and a band of no trend setting the boundary between North-Pacific and tropical-Pacific variability patterns; in the Atlantic, the northeast Gulf of Mexico shows cooling, while the western Gulf of Mexico and the Caribbean have been warming for more than three decades. Potential interactions with fisheries and coastal sensitive ecosystems are discussed.

Modeling Geoduck Growth: Multimodel Inference in Panopea globosa from the Southwestern Baja California Peninsula, Mexico

ABSTRACT Studies about individual growth for geoducks are relevant because they allow an understanding of biomass production and its maintenance in the population. This study presents the first growth curves for Panopea globosa from the southwestern Baja California Peninsula. Geoduck samples were collected from November 2006 to October 2007 in Bahía Magdalena (n = 392). The morphological data for live individuals were obtained and their ages were estimated from the right shell by counting band growth from a thin section cut from the hinge plate region. The length-at-age data were fitted to six growth models—Gompertz, Johnson, von Bertalanffy growth model (VBGM), generalized VBGM, Richards, and Schnute—using a negative log-likelihood function. The models were analyzed using multimodel inference to select the best candidate growth model based on the Akaike information criterion. The results indicate the size structure from Bahía Magdalena has a unimodal shape and shows negative allometric growth in the relationship between shell length and total weight (b = 2.4). Shell lengths varied from 93–206 mm and total weight ranged from 332–2824 g. Age validation was based on the marginal increment ratio, and suggested the growth line and band were deposited annually. Growth line formation occurred annually between January and April, and the growth band was deposited from June to December. A dominance of older year classes, from 13–22 y, was noted along with an estimated maximum age of 47 y. Based on multimodel inference, the Gompertz growth model was the best candidate for estimating growth for P. globosa. The estimated parameters included an asymptotic size of 167.51 mm, the rate at which the asymptotic size was reached was 0.218, and the age at size 0 was 0.003. These growth parameters for P. globosa from the southwestern of the Baja California Peninsula show the length at age in this region is greater than in the central Gulf of California, suggesting that management rules must be based regionally.

Review of long term macro-fauna movement by multi-mecadal warming trends in the Northeastern Pacific

Worldwide marine ecosystems are continuously responding to changes in the physical environment at diverse spatial and temporal scales. In addition to the seasonal cycle, other natural patterns occur at the interannual scale, such as El Nino-La Nina Southern Oscillation (ENSO) with a period of about three to five years (Wang & Fiedler, 2006). When ocean conditions stay above or below the long-term average for periods of 10 to 20 years we recognize decadal fluctuations (Mantua et al., 1997), and those with periods longer than 50 years are known as regime (Lluch-Belda et al., 1989). On the ocean, marine populations respond to these variations in different ways, such as changes in their distribution and abundance. Evidence suggests that this multi-decadal scale climate variations are cyclic, which generates recurrent changes in the production level of marine ecosystems in ways that may favor one species or a group over another. Abrupt changes between multi-decadal phases are known as regime shifts (Overland et al., 2008). The best documented regime shift in the North Pacific occurred in the mid-1970, with strong physical and biological signals, including ocean productivity (Ebbesmeyer, et al., 1991; Roemmich & McGowan, 1995), strong biomass and distribution changes in sardine and anchovy populations (Kawasaki, 1983; Lluch-Belda et al., 1989), and several other fish populations (Beamish et al., 1993; Mantua et al., 1997; Holbrook et al., 1997). These changes impacted marine food webs and ultimately affected the distribution and survival of marine top predators such as seabirds and marine mammals (Trites & Larkin, 1996; Veit et al., 1997; Trites et al., 2007). In this work we review published reports on long term macro-fauna (nekton) movements as related to multi-decadal temperature trends in the Northeastern Pacific.