Intro

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The “Abalone” Haliotis fulgens is one of the most economically imporatant species in Baja California. This document is a small exploration of the population dynamics of abalones around Isla Natividad. Click here if you want to see or change the code. Or click here if you want to see the data we used for this analysis.

Data Availability

The following table is the data available for Isla Nativida and Bahía Magdalnea. The Data for El Rosario is being cleaned up at this moment. But when is ready, It will be posted here

##       
##        IslaMagdalena IslaNatividad Rosario
##   2006             0           678       0
##   2007             0           217       0
##   2008             0           242       0
##   2009             0           238       0
##   2010            96           317       0
##   2011           214            41       0
##   2012           114            48       0
##   2013            21            93       0
##   2014           122           218       0

The data for these invertebrates were collected inside and outside Marine Protected Areas

Analysis

Size frequency

Size frequency of green abalone in Isla Natividad inside and outside Marine Protected Areas (MPAs)

Then I used the Kolmogorov-Smirnov Test to test whether the size of the abalones inside and outside reserves are likely to be different, i.e. comparing different distributions. Strictly speaking, the p-value gives us a probability of whether or not we can reject the null hypothesis, which is that two datasets have the same distribution.

Natividad Two-sample Kolmogorov-Smirnov test

ks.test(CabNatOut$Diameter_cm_Corrected, CabNatIn$Diameter_cm_Corrected)

## Warning in ks.test(CabNatOut$Diameter_cm_Corrected, CabNatIn
## $Diameter_cm_Corrected): p-value will be approximate in the presence of
## ties

## 
##  Two-sample Kolmogorov-Smirnov test
## 
## data:  CabNatOut$Diameter_cm_Corrected and CabNatIn$Diameter_cm_Corrected
## D = 0.077084, p-value = 0.02485
## alternative hypothesis: two-sided

Size frequency of green abalone in Bahia Magdalena inside and outside Marine Protected Areas (MPAs)

##         Fished Reserve
## Min.      5.00    5.00
## 1st Qu.   9.00   10.00
## Median   11.00   13.00
## Mean     11.06   12.03
## 3rd Qu.  13.00   14.00
## Max.     18.00   18.00
## NA's     19.00   11.00

Magdalena Two-sample Kolmogorov-Smirnov test

ks.test(CabMagOut$Diameter_cm_Corrected, CabMagIn$Diameter_cm_Corrected)

## Warning in ks.test(CabMagOut$Diameter_cm_Corrected, CabMagIn
## $Diameter_cm_Corrected): p-value will be approximate in the presence of
## ties

## 
##  Two-sample Kolmogorov-Smirnov test
## 
## data:  CabMagOut$Diameter_cm_Corrected and CabMagIn$Diameter_cm_Corrected
## D = 0.16516, p-value = 0.001356
## alternative hypothesis: two-sided

This result suggests that there are no significant size differences between abalone inside and outside MPAs in Isla Natividad and Bahia Magdalena.

Time series size

Next we looked at the size time series

## null device 
##           1

Time series relative abundance

However, if we look at the relative abunance of green abalone in Natividad insisde and outside the reserve

## null device 
##           1

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Green Abalone