1 23 Ecosystems ISSN 1432-9840 Volume 18 Number 1 Ecosystems (2015) 18:45-61 DOI 10.1007/s10021-014-9811-3 Management Forcing Increased Specialization in a Fishery System J. Hentati-Sundberg, J. Hjelm, W. J. Boonstra & H. Österblom