The appellant appeals from an order1 of the Public Employees Relations Commission (PERC) upholding the hearing officer’s determination that the appellant violated Section 447.501(l)(a) and (b), Florida Statutes (1987), by abolishing its paid full-time fire department in retaliation for positions taken by the appellee during collective bargaining negotiations. We agree with PERC’s order concluding that there was competent substantial evidence to support the hearing officer’s (1) rejection of the appellant’s assertion that the decision to disband the fire department was done for purely economic reasons, without consideration of union activities, and (2) finding that the appellant’s motivation for terminating the paid fire department was in retaliation for positions taken by appellee during negotiations and that appellee would not have, in the absence of such anti-union motivation, replaced all bargaining unit employees with volunteers. See Pasco County School Board v. Florida Public Employees Relations Commission, 353 So.2d 108, 117 (Fla. 1st DCA 1977). There was no basis for PERC to have rejected such findings by the hearing officer.

Appellant asks this court to determine whether a city’s decision to abolish its paid fire department and replace it with a volunteer department is a management decision or a mandatory subject of bargaining. In view of the above referred findings of the hearing officer and PERC, we decline — as did PERC — to issue what would amount to an advisory opinion on that sub*366ject. This court has held that it will not issue an advisory opinion on a matter not ruled upon by PERC. City of Ft. Lauderdale v. Fraternal Order of Police, Ft. Lauderdale Lodge 31, 543 So.2d 320 (Fla. 1st DCA 1989). This is simply an unlawful motivation case. A city’s decision to abolish its paid fire department and replace it with a volunteer department may indeed be a management right. But the law is clear that a public employer cannot exercise a management right in retaliation for positions taken by its employees in collective bargaining negotiations. See Pasco County School Board v. Florida Public Employees Relations Commission, 353 So.2d 108 (Fla. 1st DCA 1977); Town of Pembroke Park v. State ex rel. Healy, 446 So.2d 198 (Fla. 4th DCA 1984). The appellant’s argument that since the right to abolish its paid fire department in favor of a volunteer department is a management right “then the City should be able to make that decision at any time as long as it ‘cleansed’ itself from the earlier decision found to be infused with anti-union animus” is unavailing because the appellant failed to demonstrate to the trier of fact that it had in fact cleansed itself of its anti-union animus.

We therefore affirm the subject order. We also affirm the order’s award of a reasonable attorney’s fee and costs in favor of the appellee.