Ernesto Jardim - página pessoal

Submetido à Fisheries Research em 29/Junho/2006 (versão submetida).

Ref.: Ms. No. FISH896 Geostatistical Assessment of Sampling Designs for Portuguese Bottom Trawl Surveys Fisheries Research Dear Dr. Jardim, I can now inform you that the Editorial Board has evaluated the manuscript FISH896: Geostatistical Assessment of Sampling Designs for Portuguese Bottom Trawl Surveys. The Editor has advised that the manuscript will be reconsidered for publication after major revision. The comments below should be taken into account when revising the manuscript. Along with your revised manuscript, you will need to supply Revision notes in which you list all the changes you have made to the manuscript, and in which you detail your responses to all the comments passed by the reviewer(s) and the Editor. Should you disagree with any comment(s), please explain why. To submit a revision, please visit http://ees.elsevier.com/fish/ and log in as an Author. You will see a menu item called Submission Needing Revision. The revised manuscript and covering letter can be submitted there. You are kindly requested to submit your revised manuscript within 90 days. If your revision is received after that deadline, it may be treated as a new submission. Kind regards, Antoinette van den Brakel Journal Manager Fisheries Research fish@elsevier.com Important note: If a reviewer has provided a review or other materials as attachments, those items will not be in this letter. Please ensure therefore that you log on to the journal site and check if any attachments have been provided.

Reviewer #1: Report on manuscript "Geostatistical Assessment of Sampling Designs for Portuguese Bottom Trawl Surveys" by Ernesto Jardim and Paulo J. Ribeiro

General evaluation: Acceptable after minor revision

This is an interesting, straightforward manuscript assessing the effect of sample size and spatial configuration of Portuguese bottom trawl surveys in fish abundance estimates through geostatistical methods. The writing is clear and the figures and tables appropriate. The simulations are carefully designed, including the simulated data and the set of correlation parameters with their respective maximum likelihood estimates.

General Comments

1. Line 100. "The spatial model assumed here is a Log-Gaussian geostatistical model".

In the discussion section, the authors justify the use of isotropic models (lines 338 to 341) but no explanation and/or justification about the log-Gaussian geostatistical model selected are given. Further explanation about the reasons of the model selection will clarify the results.

2. Line 241. "Table 2 summarizes the checks of the results of the parameter estimates which were considered satisfactory and coherent".

It is not thoroughly clear in the text what the authors mean with satisfactory and coherent. More detail will be relevant to better understand the sampling design and survey processes

3. Line 347. "Furthermore, the results can be retained for all species with a spatial behaviour covered by these parameters".

It seems like the authors assume all the species surveyed have similar spatial behavior. This is not necessarily true, especially if the survey is targeting species with different life history traits and aggregation behaviors under different spatial scales (i.e. demersal fishes vs. sedentary invertebrates). Furthermore, the autocorrelation structure in the data is not explicitly mentioned or described. Additional information and discussion on the effect of spatial correlation for the different stocks targeted by the trawl survey on the model selection will improve the robustness of this study.

Minor comments

Line 123: repeated word: the the Line 125: Unnecessary word: are Lines 183 and 206: different notation for sampling designs <LAMBDA>d and ?d Line 234: confusing sentence/notation: "…and also included in the Table ®…" Table 3: Summary statistics units are not specified. Figure 1: X and Y axis legends should be specified (i.e. Longitude West and Latitude North respectively). Figure 2: Variables in the X axis are specified in the legend but not in the figure

Reviewer #3: I propose rejecting this submission because it is overly detailed on the simulation results, gives little insight how the simulations relate to the original Portuguese survey data, of which little is spoken, and because it is not clear why this is to be considered more than an exercise confirming what already has been stated in Diggle and Lophaven. The authors do show an understanding of the issues involved in simulation and did not, in my mind, make any errors. Some of the results are technical and issues of isotropy, parameter estimation and the like are discussed at a more technical level than would be understood by a general reader. The one significant result is that when there is autocorrelation in the underlying data it is better to use a combindation of regular survey with paired random additions (to provide points close to each other and better estimate autocorrelation I presume) than a pure random design for fisheries surveys. If this is indeed a new result (I'm really not sure whether it is) then this could be acceptable as a greatly reduced in size 'note' that gives the results and refers to a web document or report for details of the simulations. Certainly the geostatistical equations are not needed and are better found elsewhere. They are not new to the fisheries literature. Finally, in simulation work like this I am left unsure how general the results are to other areas. This the authors discussed some and think the results are general (maybe they are). There is little need in that case to focus on the real system. Otherwise, some evaluation using actual data would be useful (if there were a year when higher sampling intensity was used – it could be subsampled to see how much the estimates changed). In fairness to the authors I did not study the results in detail. Maybe someone who does will find gold in it. I did not think it was worth looking.

From the Editor-in-Chief : One reviewer asks for relatively small changes, while the other feels the paper is not acceptable unless it is substantially shortened and focused on what is new. If the authors will react to the reviewers comments , I will reconsider the assessment.