DOI: 10.5061/dryad.zcrjdfnpm
title: Larval anchovy and sardine abundances between Punta Eugenia and Point Conception from 1963-2015

description: Anchovies and sardines are some of the most economically and ecologically
 important and well-studied fishes on earth but there is still uncertainty
 regarding how distributions and abundances change through time and
 space.  We bring together  larval abundance data for
 northern anchovy (Engraulis mordax) and Pacific sardine (Sardinops sagax)
 collected by United States and Mexican scientists over 50 years
 (1963-2015) to test the Basin and Asynchrony hypotheses. The Basin
 Hypothesis states that a species’ geographic range and spawning area (R)
 increases with overall abundance (A) according to a power law, R=aAb,
 where the exponent (b) is less than ~ 0.5 when the rate of increasing area
 occupied saturates as population size increases. The Asynchrony Hypothesis
 postulates that anchovy and sardine abundances are negatively correlated
 through time. We found that the Basin Hypothesis was supported for both
 species but the Asynchrony Hypothesis was not during this 53-year period.
  Due to collaboration between U.S. and Mexican scientists we were
 able to better understand how two important fishes utilize their
 environment. 
description: CalCOFI and IMECOCAL collected fish larvae (ichthyoplankton) with
 obliquely-towed ring nets (1951 to 1977) and bongo nets (1978-present;
 Ohman and Smith, 1995; Thompson et al. 2017).  Detailed sampling protocols
 can be found in Kramer et al. (1972) and Smith and Richardson (1977), but,
 briefly, nets were towed to 140 meters (or within 15 m of the bottom at
 shallow stations) from 1951-1968 and then to 210 meters after 1968 (Ohman
 and Smith 1995).  Plankton in ring nets and starboard side of the bongo
 net were preserved in 5% buffered formalin, while, beginning in 1997,
 contents of the port side net were preserved in 100% ethanol (Gold et al.
 2023); here, we focus on just formalin-preserved samples.  In the
 laboratory, all larval fishes were sorted from the rest of the plankton
 and identified to species.  Whereas it is not possible to identify all
 ichthyoplankton to species (e.g., rockfishes; Thompson et al. (2016)),
 anchovy and sardine are readily identifiable at all life stages. To
 account for any differences in tow depths or the amount of water filtered,
 raw abundances were standardized by multiplying by standard haul factor
 which accounts for the volume of water that was filtered (SHF; Smith and
 Richardson, 1977) and divided by the percent of the sample sorted (100% of
 most samples were sorted but in cases where zooplankton biomass was very
 high a fraction was sorted).  These adjustments make it possible to
 directly compare samples across the time series despite some changes to
 sampling methodology through time (Thompson et al. 2017). The units of
 abundance from the net tows are reported as “number under
 10m<sup>2</sup>”, which is the number of larvae in a column of
 water with area 10m<sup>2</sup> extending downwards to the
 depth of the tow.
description: # Larval anchovy and sardine abundances between Punta Eugenia and Point
 Conception from 1963-2015
 [https://doi.org/10.5061/dryad.zcrjdfnpm](https://doi.org/10.5061/dryad.zcrjdfnpm) ## Description of the data and file structure The data here are larval abundances for anchovy and sardine collected from individual stations off the U.S. and Mexico from 1963-2015.  The column, cruise depicts the numeric cruise number where the first two digits are the year and the second two the month when the cruise began.  For example, cruise 6301 was initiated in January, 1963. The column ship is a two digit code referring to the ship that collected the larvae.  For example, "BD" is a ship named the Black Douglas. CalCOFI/IMECOCAL has a system for the longitude and latitude of sample stations.  CalCOFI "lines" are are latitudinal and "stations" are longitudinal.  A sampling location with a lower the "line" number is further south, while a station with a lower value is closer to shore. The columns longitude and latitude define the actual location where a sample was collected. The units are decimal degrees. Most CalCOFI/IMECOCAL cruises were conducted quarterly, and the column season defines the time of year of a cruise, where Dec, Jan and Feb are winter, March, April, May are spring, June, July, August are summer, and September, October, Nov are fall. Finally, Sardinops.sagax and Engraluis.mordax are larval abundances for sardine and anchovy respectively in units of number under 10 m^2 ### Files and variables #### File: sardine\_anch\_data\_for\_Dryad.csv **Description:**  ##### Variables * cruise: cruise name in year, month * ship: ship code * line: CalCOFI "line", which changes with latitude * station: CalCOFI "station", which changes with distance from shore * longitude:  Longitude of sample location in decimal degrees * latitude:    Latitude of sample location in decimal degrees * year: year of sampling * season: season of sampling * Sardinops.sagax: sardine larval abundance * Engraulis.mordax: anchovy larval abundance ## Code/software This data is just in an excel .csv format ## Access information Other publicly accessible locations of the data: * [https://coastwatch.pfeg.noaa.gov/erddap/search/index.html?page=1&itemsPerPage=1000&searchFor=calcofi](https://coastwatch.pfeg.noaa.gov/erddap/search/index.html?page=1&itemsPerPage=1000&searchFor=calcofi)