Mussel adhesive proteins (MAPs) are excellent bioadhesives. Although the role of L-3,4-dihydroxyphenyl alanine (DOPA) in water-resistant strong adhesion has been extensively studied, MAP aggregate formation and physical adsorption behavior have not been thoroughly explored. Here, we investigated the aggregation and attachment properties of a recombinant MAP with no DOPA residues. We found that chemical cross-linking of oxidized DOPA residues was not required for aggregate formation; increased anionic kosmotropy and cationic chaotropy allowed aggregation permitting strong adsorption onto hydrophilic surfaces. This study suggests that the initial step in MAP adhesion might thus be aggregation. Physical adsorption can be adjusted by varying the salt ions in water, to mediate initial efficient attachment followed by DOPA-mediated water-resistant strong adhesion.