Most people publishing in scientific journals are aware of what plagiarism is, but fewer think about the concept of self-plagiarism, except for maybe the idea of duplicate publishing of the same study. However, less clear, but nonetheless of concern, is the reuse of text repeated verbatim or nearly verbatim from one paper to another without acknowledging that the ideas/text in the new paper were presented in a prior publication. While there is an ongoing debate about how much redundancy without attribution from one paper to another by the same author is acceptable, it is best to avoid cutting and pasting language from one paper to another, or to make only a word or two change to avoid it being identical. Many journals have no explicit policy on this matter, and until recently this has been the case for Marine Mammal Science. However, the occurrence of several cases of self-plagiarism raised by reviewers of papers or Associate Editors over the past year has brought this issue to a point where it has become important to make potential authors of papers submitted to Marine Mammal Science aware of the issue and the policy of this journal.
Marine Mammal Science believes that repeating text (full sentences or paragraphs) verbatim or nearly verbatim from previously published papers without giving proper attribution is not acceptable, whether the paper from which the text has been taken was by another author (plagiarism) or the same author (self-plagiarism). When the issue of plagiarism is raised by a reviewer or Editor, the paper will likely be rejected without the ability for resubmission, although cases deemed minor may be given the opportunity to be remedied. Major cases may also be brought to the attention of the author’s institution. When the issue is self-plagiarism, the nature and extent of the overlap in text will be examined through software that cross references published material, and a determination of the course of action that should be taken will be made by the Editor in consultation with Wiley publication ethics advisors. It is recognized that methodology often follows previously developed methods, and thus descriptions may be the same or similar. This is fine but authors must be sure to acknowledge the source of previously published methodology. If it is large amounts of text verbatim, use quotation marks along with the source, but if it is paraphrased, providing the source is sufficient. Consideration of a first case of self-plagiarism for an individual author will likely not result in a rejection or retraction, but the author will be notified in writing and be required to revise the paper appropriately. The author will be cautioned that a second offense would likely result in rejection/retraction of the paper and future submissions by the author would be checked by the cross-referencing software before being considered.
Please see the following for discussions of self-plagiarism:
 Interim reports, manuscripts and many government documents are not considered published material even if they might be available through the internet or other means. What is key to making something published is the transfer of ownership and distributing the material for redistribution (from U.S Copyright Law of 1976). One could thus use language from such a non-published source they wrote without citing the source and not commit self-plagiarism. If uncertain, it is always best to cite a source.