1. Introduction
The
The biomass and standing crop of
This is the first time that the temporal variability of harvest, effort, and harvest per unit effort (CPUE) as an indicator of the abundance in each of 15 harvested beds of
2. Data and methodology
Daily records from 1956 to 1999 were provided by Productos del Pacifico, S. A. de C. V. These contained the information of harvest date, name of the bed, number of trips, and harvest size (wet weight). Total data were extracted from 3 230 daily records. For the period 1993 to 1999, additional information was obtained of the time of harvest from 638 records. With these data we estimated the monthly, seasonal, and annual values of harvest, effort and harvest per unit of effort for each bed and for the full region. The difference in the storage capacity of the two ships was weighted according with Casas-Valdez et al. (2003).
We selected as units of effort: a) the number of trips and b) the time of harvest. The harvest per unit effort (CPUE) (volume of harvest per trip made by each ship or volume of harvest per hour of harvest), was calculated with the equation-
Where: C = volume of
Seasonal harvest, and harvest and effort per category were compared using an ANOVA analysis with the software Statistic 7.0. The significant difference among treatments was determined using the Tuckey test. The relationship between the harvest of
3. Results
3.1. Harvest, effort, and CPUE in Macrocystis beds
The harvest of
The historical series of harvest and effort of the 15 beds of
Considering the average harvest and the effort applied during 49 years the
3.2. Seasonal variation
The harvest of
4. Discussion
From 1958 to 2004, the average harvest of
The lowest harvest and effort recorded in category I can be related to: a) the harvest being suspended in beds 11 (1978), 06 (1985), 07 (1984), 02 (1991), and 01 (1993), b) the long distance from the beds to the base port, bed 12 (12 h 20 min), 13 (13 h), 14 (16,5 h), and 15 (20 h). The highest harvest and effort recorded in category III can be related to a) a high productivity of the bed and, b) the short distance from the bed to the base port (5 h). In relation to the previous information, Roberto Marcos (com. pers.) noted that the quantity of effort used at each bed depended on the productivity of the bed and its cost of operation, which are related principally to the distance that the ship most run from the base port to the bed. Guzmán et al. (1971) and Corona (1985) mention that the more productive beds for 1956 – 1968 and 1974 – 1985 were the beds 03, 04, 08, 09, and 10 that are in categories II and III of this study. The largest harvest of
Along the northwest coast of the Baja California Peninsula the greatest upwellings are during spring and summer (Casas-Valdez, 2001) and have high nutrient concentrations and lower temperatures (Lynn & Sympson, 1987; Parés & O'Brien, 1989) that favor the development of
The CPUE was used as indicator of abundance for
In our study, we considered that the CPUE shows the changes in the abundance of
The surplus production models of Schaefer and Fox were used to assess the fishery condition of
5. Conclusions
The
Along the northwest coast of the Baja California Peninsula, the highest harvest of
The harvest per unit of effort (CPUE) was more stable in the beds where more effort was used, as in the beds at Punta Mezquite, Salsipuedes, Bahía de La Soledad, Santo Tomás and Punta China, whereas in the beds where less effort was used the CPUE was more variable.
Acknowledgments
Thanks to Productos del Pacifico, S. A. de C. V. for providing the data of harvest of
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